I tried to make the mountain dew cupcakes and icing posted in cake central.  The recipe for the icing calls for 2 cans of condensed milk and 2 cups of butter to be whipped until thick.  It never thickens.  Any suggestion on how to make it thicker or what the issue may be?  I suspect that 2 14oz cans was too much.  

The recipe was posted in the Recipe section not as a forum topic.  It didn't say to add any powdered sugar.  I did send the one who posted the recipe a message.  Was hoping someone had some ideas.
 

I have never used the recipe, but I can't imagine those two ingredients would come together and make anything but a soupy mess.

Was it maybe meant to be used as a glaze?

One thing you can do if you want Mt Dew flavour, is reduce the soda down to a syrup, then mix it into your regular butter cream, since it's so sweet I would suggest an IMBC with the sugar reduced a little.

can you post which recipe you used? I did a search, and can't find any that call or 2 cans of each of those.

Here is the link http://cakecentral.com/a/mountain-dew-cupcakes

If you read what she says, she got the recipe from allthingscupcake.com. When you go to the site and check the recipe, it has powdered sugar in it. 

http://www.allthingscupcake.com/2007/12/05/mountain-dew-cupcakes/

Mountain Dew Buttercream

1 cup butter (2 sticks)
4-5 cups powdered sugar
2 tablespoons Mountain Dew
Juices from half of 1 lemon and half of 1 lime.
Lemon and lime zest (rest of zest from cupcake recipe. Or zest from half of 1 lemon and 1 whole lime)
1 teaspoon lemon extract
neon green food coloring (yellow and blue if you dont have green)

1. Sift powdered sugar into a bowl or onto parchment
2. Beat butter at medium-high speed until creamy
3. Add half of the sugar, turn mixer on low for 5 seconds.
4. Add the Mountain Dew, zest, and lemon extract . Beat until combined.
5. Add food coloring to the desired color.
6. Gradually add remaining sugar until you get to the consistency and sweetness you like.

Oh my, I totally misread your original post!

I had it in my head you mixed 2 cans of mt dew and 2 cans of the condensed milk! haha, I need coffee!

How long did you beat it for? It looks like about 10 minutes on high is the norm.

It seemed like an eternity, was definitely longer that 10 mins.  I've also looked at some other recipes for Mountain Dew Cupcakes on other sites and none of them use condensed milk.  She did note that she tweaked the recipe.  Hopefully she will be able to reply to my message to her directly.  There was another post under that recipe of someone who had the same issue I did with it being too soupy even after 20 minutes on high speed with a stand mixer. 
 

Thanks.  I also noticed on other sites that none of them refer to using condensed milk.  Will try one of the other icing recipes for it.