Preheat oven to 325º F. Place cupcake liners in muffin tin. Spray the liners lightly with cooking spray.
Combine flour, sugar, cocoa, baking powder, baking soda, salt and espresso powder to a large bowl.
Whisk to combine.
In the same bowl, add milk, vegetable oil, eggs, and vanilla to flour mixture and mix together on medium speed until well combined.
Reduce speed to low and add boiling water to the cake batter.
Once water is added, beat on high speed for about 1 minute to add air to the batter.
Evenly distribute cake batter until each liner is about ¾ full.
Place in the oven and bake 12-15 minutes or until a toothpick inserted comes out clean.
Remove from the oven and allow the cupcakes to cool completely before frosting.