AHi! I am very new to this thread and have only been baking cakes professionally for a year now. First, I want to emphasize that I am a baker, not a decorator. I have so much admiration for those who create with frosting and fondant. I bake layer cakes for a local coffee shop/wine bar/cafe. I frost them and add accent toppings, and that is the limits of my abilities and patience :D I inherited the job and recipes from another baker, and have since tweaked and added some things.

To the point, I am having some issues with my chocolate cake. My predicessor could never get the collapse out of the cake. She used ap flour, so I gradually switched to cake flour. The recipe is heavy on leaveners and acids (1T baking powder and soda to 3 1/2 C flour, 2c buttermilk, 2c cooled coffee). Recently the cake has started to spill out of the pans it used to bake beautifully in.

These are heavy Williams Sonoma pans, and my convection oven is less than a year old. The owner does the grocery shopping, and has been buying extra large eggs lately despite my protests >:( I also bake the cake on convection, when the recipe isn't written for it, and just had subtracted ~5 of the 45 minutes. In addition to overflow the cakes taste a bit acid-y to me. Oh, my predecessor also used coffee crystals and water, and I switched to the coffee shop's own coffee (because, really??). The recipe also calls for 2 1/2 minutes of beating at high speed before stirring in the coffee.

I now have to put a pan under them because about 50% of the time they ooze volcano-like. So, my question is, out of all these changes, what might be the cause? I can offer more details too, but I feel like I'm rambling and endangering your patience and willingness to help me :D

I am  not a baker per se, I do bake my own cakes, I just follow recipes so my help may be limited.  I will say this, anytime you 'tweak' a baked item, you can screw it up big time.  There's such a precise science to it, unless I was sure of what the chemical reaction to whatever I was doing was going to be, I'd question whether to do it at all. 

I've always found chocolate cakes to be a challenge.  They seem to do better on non-humid days I've discovered.  The fact that you switched types of flour could be an issue...you might not need as much baking soda or powder as a result.  Your oven could need calibrating.  The fact that you're using additional liquid by using coffee instead of the powdered could affect the outcome.   Other bakers will come to your rescue I'm sure...these are a few things I thought of.  Good luck!
 

ABaking powder and soda can go bad. They lose their leavening power over time. Perhaps these recipes were working before with old leavener? You got new stuff with way more bang? The egg issue is easy enough to fix. One large egg is 50g. Crack some eggs, scramble them, and weigh out the equivalent you need. This could easily be contributing to your volcano. You say it happens 50% of the time. Are you using a timer for the 2.5 min? Overbeaten eggs can cause baked goods to overinflate and then collapse. Lastly, try lowering the oven temp 25 degrees and/or only filling your pans halfway.

Could you be using a HIGH Ratio cake flour by chance??  I found when I bought 50 lbs of HI RATIO cake flour my cakes sprung out of their pans using the same recipes I had used another cake flour or recipes that used just AP flour.

I have yet to figure out what to do about it...but putting less batter in the pans worked for me and I got a lot of cupcakes out of the extra batter. 

40 lbs more of HI RATIO...so I've got time to keep looking for the solution...LOL.  I might add that Hi Ratio cake flour makes a nice white wedding cake...but it did require pushing down with a towel after leaving the oven. 
 

i can't follow all the tweaking back and forth

i'd recommend tossing that formula and starting over with one that works then let the tweaking commence

for example colette and toba each have stunner choco cake recipes with similar ingredient gene pools

see if i can find them online...

http://www.epicurious.com/recipes/food/views/Chocolate-Fudge-Cake-109712

http://www.bakespace.com/recipes/detail/Colette's-Chocolate-Cake/28300/

toba's has soda only plus buttermilk and brown sugar etc

colette's has milk plus both soda and bkg powder etc

so each of these has the science you are looking for

combine them as you will

or regroup your recipe back to these

Thanks so much for all the tips. Unfortunately, there is nooo way I can just scrap the recipe. It has a huge following at the cafe, and I've had a few requests to make it for weddings (to which I kindly, politely said -- no way. Let one of the professional local cake businesses handle that). The end result does taste fabulous, and I bake about two of these cakes a week, so other people agree :) It's more that I wanted the recipe to be more consistent, because the former baker had so much trouble with rounding and collapsing. My changes are really in pursuit of a consistent, even cake.

I wonder if the full switch to cake flour combined with large amount of buttermilk (2C), plus brewed coffee instead of a weak water/instant crystals mix is the cause of my overflow. I had been switching gradually to cake flour, because I was unsure of what it would do. I had a 2C cake, 1 1/2C ap flour blend, and was using that for several months. Just recently I switched to all cake flour, so I'm guessing that is my root cause.

My leaveners are definitely in top shape. Like I said, since I bake these so often, my powder and soda is never open for longer than a month (I also bake muffins, so I use scads of baking powder in my house). I have used both Dutch process and "regular" cocoa, and while I like the Dutch cocoa flavor, I usually use Ghiradelli because it's what my boss can easily order in. I can't say that I noticed any difference in baking between those two cocoas. 

I also know that this is a super duper thin batter. Before the coffee is added, it is nice and thicker, more like a "brownie" or box cake consistency. I'm unsure of where this recipe comes from, or if my predecessor tweaked it before I got it.

I did go ahead and lower the baking soda to a 1/2 T yesterday when I baked the cake. I also switched back to 1C ap flour and 2 1/2 C cake flour. It came out slightly more dense, with a more rounded top (this cake had otherwise baked very flat). I like the flavor still - a bit fudgier texture was nice. I think I have a better direction for tweaking this recipe now.

If you are working with 3.5 cups flour and 4 cups of liquid (2c buttermilk + 2c coffee) before you add any fats, its no wonder its spilling over the sides especially with that amount of leavener (am I reading you correctly 1 Tablespoon each baking powder and baking soda?  or is it one Tablespoon of the two combined).  What fat are you using and how much?  Also, what chocolate are you using?

A1 c of veg oil, and yes, it is 1T each of powder and soda. The recipe is cocoa powder - 1 1/2 C. I use regular, but have used Dutched in the past with no noticeable change.

I can't see that you've mentioned sugar, but I'm assuming you're using about 2.5 cups.  I would try as follows:

Use the AP flour (for structure) and the large eggs (structure and leavening).

Leave out the baking powder altogether and increase the soda by 1 tsp.

Reduce buttermilk and coffee each by 1/2 cup.

This will be quite a bit thicker before the addition of the coffee than you are used to.  The consistency after the coffee is incorporated should be somewhat like pancake batter (it will pour easily, but coat the bowl so you need a spatula to get all of it into the pans.  I wouldn't mix it more than two minutes after the eggs are added, you will get a good deal of doming if you over mix this recipe and getting the coffee incorporated itself takes a fair bit of mixing.

I start with a 350 oven (regular home kitchen oven) and turn it down to 335 once the cakes are in and the door is closed. 

OK so let me summarise the recipe from the dribbles of OP's posts:

1 cup oil

1.5 cups cocoa

3.5 cups flour

2 cups coffee

2 cups buttermilk

1 tablespoon baking powder

1 tablespoon baking soda

sugar (not specified)

eggs (not specified)

vanilla (not specifed)

This is a recipe of the type called "fudgy chocolate cake" on many websites.  I like it but I believe you need to make changes to the procedure.

You NEED 10% gluten flour.  Because the cocoa dilutes the gluten content from 10% to 7% (cocoa has starch but no gluten).  I use unbleached AP flour: unbleached means that the gluten is not partially broken down by bleaching.  The acid in the buttermilk then takes care of  any gluten development during mixing.

You need to WEIGH all ingredients for consistency.  You and your predecessor might have added 15% different amount of flour than you use.  Measure out one recipe worth and WEIGH what you measured out.  Then use those weights all the time.

I use non-alkaline cocoa for this recipe (my source recipe calls for Dutch processed). I highly recommend that you premix the cocoa and the hot brewed coffee to a paste and let that cool to room temperature. Doing this as far ahead as the day before is OK.  This will  give the batter more structure to rise in the oven without affecting the "fudgy" taste.

You NEED to use baking powder because your batter probably sits for some time after mixing.  I use baking powder for this kind of chocolate cake, no soda at all.  I would use 5 teaspoons double-acting baking powder for this total amount of  flour and cocoa.

If you use baking soda as half of your leavening, then you MUST pan immediately after mixing; the batter can then sit in pans for maximum 30 minutes before baking.  Otherwise you lose the lift.

Finally, I bake this in aluminum pans lined on the bottom with parchment, NO grease or paper on sides, and with baking strips.  These cakes bake flat even if they are 11 x 15" sheets or 12" rounds.  The cakes release themselves from the pan sides when they are fully baked, they have excellent shelf life, they are the most requested recipe that I bake.

BOTTOM LINE: I recommend ONLY that you change the leavening as far as amounts of ingredients. 

Your technique will contribute far more to the end result.

PS this is why we ask people to post the recipe when they are asking for help: we could have saved you a week of going back and forth here.

Sorry, I should have read through the etiquette page. I guess I assumed laying out the whole recipe was giving up something "secret" (which, considering this recipe is NOT an original creation, seems a bit silly to me now).

For the sake of clarity, here is the full recipe:

3 1/2 C flour (Primarily, I've done 1 1/2 C cake flour, 2 C unbleached, a.p. flour. I spoon and level my flours.)

4 C sugar

1 T baking powder

1T baking soda

2 tsp salt

1 1/2 C cocoa powder

(all but sugar is sifted, then sugar is whisked into the flour mix.)

Liquids are all completely room temp, including coffee:

4 eggs

2 C buttermilk

1 C oil

4 tsp vanilla

2 C cooled coffee

I whisk the liquids, except the coffee. The recipe calls for the mix to be beat together for 2.5 minutes (I always set a timer). Then the coffee is stirred in until just combined with a stiff silicone spatula. It is then immediately baked for 40 minutes at 350 F on true convection.

My cake does go directly into the oven within two minutes of mixing into heavyweight 9 inch pans lined with a Silpat and sprayed on the sides with Pam with flour. Like I said earlier, I have true convection, so I bake both layers at once without rotating or switching.

Last week I went ahead and baked this cake with the following changes: 1 3/4 C coffee, 2C a.p., 1 1/2 C cake flour, 1 T baking soda, 1/2 T baking powder. The cake definitely baked differently. It was a bit more dense, and my Silpat came off the bottom with some cake crumbs attached (usually it releases more cleanly). The texture was "fudgier", and it baked more domed. When this cake doesn't barf out of the pans, it does bake very level, which I love for frosting.

It seems that the volcano cake is largely the result of extra large eggs for about a month. Now that my boss is getting me large eggs again, the overflow isn't happening. However, I still want to tweak this recipe so that it is more consistent in texture.

Should I perhaps lower the temperature since I bake on convection, which the recipe doesn't account for? The recipe calls for 45 minutes at 250. My edges are still a bit more crusty than I would like. But will lowering the temperature also contribute to a more domed end product?

Seriously, this is why I love cooking so much more than baking. All this science!

Oh, and I definitely appreciate a recipe with weights and grams instead of cups. My carrot cake recipe is in grams, and it never fails me. I've hesistated to weight and convert the recipe mainly because I'm not so pleased with my results, so I want to fix it before I lock it in, if that makes sense?

AThe recipe you posted is the Hershey's perfectly chocolate chocolate cake recipe with the following modifications: 1. It's doubled. 2. Buttermilk instead of milk 3. Coffee instead of boiling water.

I'd suggest starting with Hershey's recipe and tweak that one.

Definitely stick with the All Purpose flour.  It has a higher protein content and will make a cake with more structure as  stated above.

It is exactly Hershey's, as Sassyzan said.  Use the coffee hot and put the cake right in the oven. .Use the AP flour.  It should be more consistent then.
 

As above:  You do NOT need to use the cake flour.  It is contributing to the issues you are experiencing.

I have nothing to contribute to this thread except that this reminds me of the Friends episode where Phoebe is freaking out that she didn't get her Grandmas (?) cookie recipe before she died (or something like that) and she's like, "It's a secret recipe by Toullehausse".  LOL ended up it's the Toll House recipe.

Your cake will bake a lot better if you use THREE 9" pans.  The cake will bake with a lot less crust and it will retain the "fudgy" character better.  Baking time less than 25 minutes at 350F when the batter is thinner.

I make justabout this recipe (mine has 4 XL eggs) and I bake it in an 11 x 15.  Batter is 1" thick and it takes 35 minutes at 350F (gas or electric conventional).

You will need to stack all three layers to get the right height.  No problem, just a little more filling...but so much less frustration in the oven.

A