Preheat the Oven:
Set oven to 350°F (175°C). Grease and flour a Bundt pan.
Mix Dry Ingredients:
Sift flour, cocoa powder, baking powder, and salt into a bowl.
Prepare Wet Ingredients:
In another bowl, whisk eggs, sugar, brown sugar, vanilla, espresso, sour cream, and oil until smooth.
Combine and Mix:
Gradually add dry ingredients to the wet mixture. Stir until just combined.
Bake the Cake:
Pour batter into the pan. Bake for 50 minutes or until a toothpick comes out clean.
Cool the Cake:
Let it rest in the pan for 10 minutes, then transfer to a cooling rack.
Make the Glaze (Optional):
Mix powdered sugar, melted butter, and espresso. Drizzle over the cooled cake.
Slice and Enjoy:
Serve warm or at room temperature. Pairs best with—what else?—a cup of coffee.