Make Boxed Cake Mix Better and Buttercream

It's Memorial Day weekend and even though I posted a cake recipe yesterday, I realize that for most people a 2 day cake isn't really family barbecue material. So here's my super fast recipe for a great cake mix cake and 3 different frostings!
There aren't any pictures because this is more of a guide than a recipe, but I'm sure you'll see pictures of similar recipes soon, especially the frostings.

Making Cake Mix Great:
Pour your cake mix into a bowl.
In a different bowl, mix the eggs called for on the box with 1 extra egg yolk.
Replace the water called for on the box with milk, and add to eggs. Mix to combine.
Add the oil called for on the box (or use melted butter), 1 tsp vanilla extract, and 1 tsp instant espresso for chocolate cake
For an extra rich cake, mix in 1/4 cup yogurt or sour cream.
Mix wet ingredients well.
Add the wet mix to the dry mixture, mix well and bake  according to the directions on the box.

Mixing the wet ingredients  before adding them to the dry will give you a finer crumb.
Feel free to mix and match the above steps and do what's convenient for you! This recipe gives you a super moist cake.

Favorite Cake Mixes:
Yellow: Betty Crocker Super Moist Yellow cake mix tastes almost exactly like the King Arthur version, but is 1/2 the price!
Chocolate:Duncan Hines Devils Food Cake
White: Betty Crocker Super Moist Cake mix in Vanilla

Frosting: Feel free to dye them patriotic colors
Classic Vanilla Buttercream:
3 cups of powdered sugar
1 cup softened butter cut into large pieces
1 1/2 tsp vanilla extract
2-4 Tbs whipping cream
With a hand mixer, beat the butter and sugar on low, moving up to medium, until they are combined and slightly sandy in texture. Add vanilla, dye, and 2 Tbs cream. Continue beating, moving up to high speed. If the mixture needs thinning, add more cream very gradually. Whip until fluffy

Chocolate Buttercream:
1 pound powdered sugar
1 cup good quality bittersweet chocolate, chopped
1/2 cup softened butter
2-3 Tbs whipping cream
pinch of salt
1 tsp vanilla
1 tsp instant espresso
Melt chocolate gently in a double boiler or the microwave. Set aside to cool for 5 minutes. Dissolve espresso in 2Tbs cream, and add vanilla. Beat the butter, sugar and salt together until well combined, about 3 minutes. Add cream mixture and beat to combine. Slowly add chocolate, raising mixer speed to high, until the frosting reached medium peaks. If the mixture is too warm, cool in the refrigerator after the chocolate is completely incorporated. Whisk again to fluff it up before using.

Summery Mint Buttercream:

3 cups of powdered sugar
1 cup softened butter cut into large pieces
1 tsp mint extract
2-4 Tbs whipping cream
3 Tbs chopped fresh mint leaves
With a hand mixer, beat the butter and sugar on low, moving up to medium, until well combines-- 3 minutes. Add mint extract and 2 Tbs cream. Continue beating, moving up to high speed. If the mixture needs thinning, add more cream very gradually. Beat until desired consistency, then gently fold in chopped mint leaves with a rubber spatula.