Hello to all the wonderful bakers,

I want to bake a 12x18x2 inch sheet cake and want to use the recipe for yellow and chocolate cake from the famous book The Cake Bible.
I previously had tried to convert the recipe for the above pan size but it was disaster.

now i am have to bake a cake for a friend's party and she wants to have a 12x18 cake with both yellow and chocolate cake layers in one cake ( or like zebra cake using both flavors). She has tasted my regular 9 inch cakes using the recipe from Cake bible and she wants the same recipe for her cake.

I really need help as i need only 1 layer of both yellow and chocolate cake.

Can anyone of you please share the converted recipe if you have.

Apperciate all your help
Thanks

I hope this is helpful:
http://www.cocoandme.com/2010/10/12/cake-pan-size-conversion-the-formula/

Am not sure if I undestand your problem but I will tell you what I normally do since I use RLB's butter cake recipes most of the time. If I feel that a single batch will not be enough for the tin size then I double the recipe (each ingrd. x2). Then I pour my batter to half full. Any leftover batter I put in an appropriate tin size (eyeball). If the two can fit in oven together, then I will bake together. If not, then I bake after. Rose says its ok to keep batter in pan. So far, I have not had problems with this. Extra cake freezes well and can be used later when the need arises.
Sometimes though, the double recipe may not be enough. I will bake the first double batch, set aside and bake another one. Then I level an fill in layers to desired height. May things work out well for you.

If I understand you correctly, you need a 12x 18 inch cake that is half yellow and half chocolate?

Since the 12x18 inch cake uses a rose factor of 8, why not make a 9inch worth of batter for each, then either pour them into the pan , one on each side, or marble them together? (not sure if you wanted it marbled or half and half)

You have to adjust the baking powder. For your chocolate cake, use 1 1/3 tsp x a rose factor of 4. For your yellow cake, use 1 1/4 tsp x a rose factor of 4. I've done this and it comes out perfectly.

Marbling RLB's yellow and chocolate butter cakes has not worked for me. Baking times are different too. I have layered them though and it works.

Thanks all for your replies, sorry for getting back late,

@rosech, Acc to RLB, we need to use the rose factor to convert the recipes for large pan sizes and when i used the conversion method, the cakes failed.

Since you mentioned you could layer the butter cakes can you please pm me the recipe you used successfully. TIA

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@karateka, if you mean having yellow and chocolate batter in the same pan, i am worried as to how it will work as chocolate and yellow cakes have diff baking pwd measure and baking times, but i was looking for more like a layer of chocolate and a layer of vanilla for a 2 layer 12x18 cake.

Hi arrira
I failed to read pm from my mobile phone. I do not have the cake bible. I use RLB's yellow and chocolate butter cake recipes according to her videos on youtube. Please note that the doubling method is not from her. Just me trying it out and it works fine. The keeping batter for a while in pan is just a tip she mentions while answering questions. Is the bigger pan of same material and color as the smaller ones? I use cm here. Will google and see conversion then tell u what I would do in that situation. So far I have done that with 30cm round and square pans. (I think its 12 inch).

These are my go-to recipes and I marble them all the time. I have never had a failure.

I've also made a black and white cake using her white cake recipe and her chocolate. People loved it.

May u please tell us more on the disaster? Was it about rising or something else?

If memory serves, a 12x18 is a half sheet, which is a rose factor of 8. Check the basic recipe for yellow cake, and multiply everything by a factor of 8. Use the baking powder amount for "sheet cakes" and multiply by 8. This should make a half sheet yellow cake.

If you want to marble yellow and chocolate, multiply the yellow by 4, and the yellow/white batter sheet cake baking powder amount by 4. Set that batter aside. Multiply the chocolate recipe by 4, the chocolate sheet cake baking powder amount by 4. Then marble the two batters together. It generally takes closer to 40 or 45 minutes to bake, and I use 2 flower nails in the center, and bake even strips around the outside (when I remember).

I use this all the time and have never had a problem.

I marble her white cake all the time - for a 1/2 sheet I'd take out about 2 cups of white batter, add in cocoa powder and a dash of canola oil, then swirl it in the white. Comes out really great. Getting the balance of the chocolate is tricky, you don't want to add to much otherwise it drowns out your white. I saw someone do this on an episode of Amazing Cakes, tried it and was shocked at how good and easy it was.

After reading the thread I don't know if this was a question, but thought I'd offer that anyway.

@karateka and @FromScratchSF,

Thanks alot for your inputs. Will try it out and hoping it will turn out alright . Also is flower nail really imp as i dont have the metal ones. i just bake regular 9in cakes with bake strips and this is my first sheet cake.

Thanks again

I have not done anything as big as 30 cmx45cm with RLB's recipe. However I had a problem with one cake which had one side being burnt the other not when I used that pan size with another recipe. Please update me when you have applied the methods mentioned here so I can use those if I get a 30 cmx45cm cake request.

I tried RLB's yellow cake with 30x45x4cm pan. Not sure what its made of. It came with the oven. I doubled every ingredient. Came out perfect. Solved my problems with my bigger 8cm deep aluminium pans which took too long for cakes to be done and cakes falling whilst cooling.

Check out this web site

http://www.realbakingwithrose.com/

When I have a customer who wants and 12 by 18 1/2 and 1/2. I will bake in 2, 9 by 12 inch pans and butt together to make a 12 by 18 inch pan. Left over batter I use to make cupcakes or bake and freeze as another person suggested.

I then have cake for cake balls as this is all I use frozen cakes for.]

Hope that helps