Combine 1 stick unsalted butter with 1-1/2 cups sugar in the mixer. Then add 3 eggs and mix on high speed for 6 minutes, or until fluffy.

In a separate bowl, combine and sift together:

1-1/4 cups cake flour

3/4 cup unsweetened cocoa

1/4 tsp baking powder

1/4 tsp salt

Once the butter, sugar, and egg mix is ready, mix half of your flour mixture in, then 1/2 cup buttermilk, then the last half of the flour mix.

I didn’t have buttermilk, but I mixed 1/2 cup regular milk with 1/2 tbsp vinegar and let it sit for 5 minutes. Not sure if this would work for soy milk.