Preheat oven to 350°F (177°C). Line a 12-cup muffin pan with cupcake liners.
In a mixing bowl or stand mixer, add the wet ingredients (sugar, eggs, oil and vanilla) and mix together at a medium speed for 1 minute.
In another mixing bowl stir together the dry ingredients (flour, baking powder, baking soda, salt, cocoa and espresso).
Add dry ingredients to the wet and mix together on low speed until all the ingredients are incorporated.
Slowly add the buttermilk. Once ingredients are incorporated, turn off the mixer.
Pour batter into the cupcake liners. Fill the liners 2/3 full. Bake for 18-22 minutes. Immediately remove cupcakes to cool on cooling rack.