Cake-y Goodness

I recently made cupcakes for the Parent Pages Rummage Sale's lemonade stand: Martha Stewart's Best One-Bowl Chocolate Cake recipe with paired with her cream cheese frosting, and Smitten Kitchen's Best Birthday Cake (a yellow cake) frosted with Martha Stewart's chocolate frosting. Smitten Kitchen's yellow cake was awesome. I had saved a few for our home and by Tuesday night they were gone. So that meant Wednesday night I was bemoaning the fact that there were no more sweets in the house. So I made cupcakes again - this time trying the Easy-Mix Yellow Cupcake recipe from Elinor Klivan's Cupcakes! book. Unfortunately, that cake didn't have the buttery richness nor the fine crumb of the the Smitten Kitchen yellow cake.

So here are the ingredients I used for Smitten Kitchen's yellow cake, converted to weights:
340g apf
60g cornstarch
2 teaspoons baking powder
1 1/2 teaspoons baking soda

1 teaspoon salt

8 oz (2 sticks) unsalted butter, at room temperature
400g sugar

2 teaspoons pure vanilla extract

4 large eggs, at room temperature

1 cup "buttermilk" made with 1T vinegar and milk to make 1 cup + 1 cup sour cream, well-shaken

Ingredients that I used for Martha Stewart's chocolate frosting:
259g powdered sugar
1/4c cocoa powder
6oz cream cheese
6oz butter
9oz bittersweet chocolate
3/4c sour cream

Yes, I know my weights go back and forth between metric and Imperial, but that's because my scale can do both and so I don't bother to convert to metric if the weights in Imperial are already provided.

Incidentally, the chocolate frosting recipe is from the April 2010 "Best" issue. The same recipe appears again in her September 2010 issue with every ingredient doubled except the butter. A typo, perhaps? Stick with the April 2010 version.