Mix the dry ingredients to a large mixing bowl or stand mixer. This would include your flour, sugar, cocoa powder, baking soda, baking powder, & salt.
Add the coffee/espresso, milk, oil, eggs, and vanilla to the dry ingredient bowl and mix until thoroughly combined. Note the batter will be thin.
Pour into prepared cake pans or cupcake liners.
Bake 30-35 minutes for 9" round cakes OR 20-25 minutes for cupcakes.
Video
Notes
The batter is very thin which gives these cupcakes a very light fluffy consistency but makes cupcake filling messy. Use a measuring cup or a cake batter dispenser (not recommended for the vanilla cupcake batter).
The stronger the coffee the more deep the cake flavor will be. If you have espresso available, use it.
I use this recipe for my chocolate oreo cupcake recipe as well. Just throw a full-size oreo into the cupcake wrapper before adding your batter. Then get them to the oven as soon as possible.