We need to set aside the dry ingredients - Flour, cocoa, baking powder, baking soda & salt. NOT SUGAR.
In a small bowl or measuring cup mix together the milk, sour cream, and vanilla. It should be thick but pourable. (I do this in a 2 cup measuring cup and it worked perfectly).
In our main mixing bowl, cream together the butter and the sugar until light yellow and slightly fluffy.
Add the eggs next, one at a time until the first completely dissapears.
Next, we will alternate adding the dry & wet ingredients. Adding Dry - Wet - Dry- Wet - Dry. This helps keep our batter nice a silky.
Scrape the bowl down as much as possible to make sure there aren't any hiding chunks of butter/sugar at the bottom or sides of your bowl.
Cupcakes
Using cupcake papers, pre-line for a dozen.
Using a portion scoop, put 1 scoop in each cup. If you don't have a portion scoop, use a ¼ cup measuring cup and fill about ¾ of the way up.
Bake at 350 degrees for about 22-25 minutes or until a toothpick pulls clean.
Cake
Make sure to butter & flour your pans so they release nicely. I use about 1 tablespoon of butter on a paper towel and rub the bottom and sides. Then add about ¼ cup of flour and shake it all around. When done, I turn them upside down and tap the bottom.
Next, evenly divide the batter between your pans. I've personally tested this recipe works for anything from 5"- 9" pans and it's worked out beautifuly.
Bake at 350-degrees oven for about 30-35 minutes or until a toothpick pulls clean.