Preheat the oven to 350°F (175°C). Grease a 9-inch round cake pan.
In a bowl, whisk together flour, baking powder, baking soda, salt, espresso powder, and cocoa powder.
Beat butter and sugar together until fluffy. Add eggs and vanilla, mixing well.
Alternate adding dry ingredients and sour cream to the butter mixture. Stir in milk.
Pour batter into the pan and smooth the top.
Bake for 35-40 minutes, or until a toothpick comes out clean.
Let the cake cool in the pan for 10 minutes, then transfer to a cooling rack.
To make the glaze, whisk powdered sugar, milk, espresso powder, and cocoa powder.
Drizzle glaze over the cooled cake.