Preheat oven to 325º F. Prepare cupcake liners in muffin tin.
In a large mixing bowl add the flour, sugar, cocoa, baking powder, baking soda, and salt. Whisk through to combine using a hand mixer or stand mixer.
To the dry ingredients add milk, vegetable oil, egg, and vanilla to flour mixture. Mix on medium low until just combined. Boil the water in the microwave, then to it add the espresso powder and mix until dissolved (caution - it may bubble).
Reduce speed to low and carefully add boiling water to the cake batter. Once incorporated, beat on high for 1 minute to aerate the batter.
Place one whole Oreo to the bottom of each cupcake liner**. Fill each liner with batter, just 3/4 full. If any Oreo's rise to the top, use a fork to push them down. Most will settle to the bottom while baking.
Bake for about 16-18 minutes, or until a toothpick inserted in the center comes out clean.
Remove from the oven and allow the cupcakes to cool completely on a cooling rack.