Preheat oven to 350°F. Line a muffin tin with paper liners.
In a large bowl, combine oil, sugar, eggs, and vanilla.
In a small bowl, combine flour, cocoa powder, espresso powder, baking soda, and salt.
Mix in half of the flour mixture into the sugar mixture. Stir in the buttermilk. Add remaining half of flour mixture. Stir in hot coffee.
Evenly distribute batter among muffin tins, filling about 2/3 of the way. Bake 18 minutes or until a toothpick inserted in the center comes out clean. Let cool completely before frosting.