Preheat the oven to 350℉ (175℃) line a 12-cup cupcake pan with cupcakes liners.
In a bowl combine & mix room-temperature milk, vinegar & yogurt. Let it sit for 5 min until it is slightly curdled to make buttermilk.
Add sugar, oil & vanilla. Mix with a hand whisk until sugar granules are dissolved and oil is combined.
Combine and sift all the dry ingredients (flour, cocoa, baking powder, baking soda) into liquid ingredients. Mix gently with a hand whisk or electric whisk until the batter is smooth.
Fill 12 cupcake liners with the cupcake batter and bake for 13-15 minutes or until firm to touch.
Let them cool completely.
Trim a very thin layer of the cupcake if desired to make cake crumbs for decorating.