Preheat & Prep
Preheat oven to 350°F. Line 10 cupcake wells with liners.
Bloom the Cocoa
In a small heatproof bowl, add 1/2 cup cocoa powder. Pour in 1/2 cup hot coffee or water. Whisk until smooth, glossy, and lump-free. Stir in 3/4 tsp vanilla. Let cool for 3-5 minutes so it's warm, not hot.
Make Quick Buttermilk
In a measuring cup, stir together 1/2 cup milk + 1 tsp vinegar. Let sit 5 minutes until it curdles slightly.
Mix Dry Ingredients
In a large bowl, whisk together flour, sugar, baking soda, baking powder, and salt.
Mix Wet Ingredients
In a medium bowl, whisk 1 egg + 1/2 cup oil until smooth. Whisk in your quick buttermilk.
Combine the Batter
Pour the wet mixture into the dry. Whisk gently until no flour streaks remain. Add the bloomed cocoa mixture, whisk again until smooth and dark. The batter will be thin - that's exactly right for moist results.
Add the Chocolate Chips
Fold in 1/2 cup chocolate chips. Divide batter between cupcake liners (about 3/4 full).
Bake
Bake 16-20 minutes, until a tester comes out with moist crumbs (not wet). For mini cupcakes: fill with 2 tbsp batter and bake 10-12 minutes.
Cool
Cool in pan for 5 minutes, then transfer to a wire rack.