Preheat oven to 350°F. Line a 12 cup muffin tin with paper liners or grease the wells.
In a large bowl, combine flour, sugar, cocoa powder, espresso powder, baking powder, baking soda and salt. Stir in chocolate chips.
In a separate bowl, lightly beat egg. Mix in oil, coffee and vanilla.
Pour wet ingredients over dry ingredients and mix just until flour is no longer dry.
Scoop batter into prepared muffin tin and bake for 20-22 minutes, or until a toothpick inserted in the center of a muffin comes out clean or with a few sticky crumbs.