Preheat oven to 350°F (177°C). Line a 12-cup muffin pan with cupcake liners.
In one mixing bowl stir together the wet ingredients (sugar, eggs, oil and vanilla).
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 stir together.
Slowly add the buttermilk.
Pour batter into the cupcake liners.
Bake for 18-22 minutes. Immediately remove cupcakes to cool on cooling rack.
Frost cooled cupcakes with frosting.