Preheat your oven to 350 degrees F (180 degrees C). Line a 9 x 5 loaf pan with parchment paper leaving an overhang on each side. Set aside.

Combine butter, bananas, sour cream, coffee liqueur, and espresso powder in a bowl and whisk until smooth. Add brown sugar and stir until combined. Add eggs one at a time, mixing thoroughly after each addition. Sift flour, baking soda, and salt into your wet mixture. Fold the dry ingredients into the batter just until combined. Be careful not to overmix.

Pour batter into prepared pan, sprinkle with brown sugar, and bake for 50-60 minutes or until a toothpick inserted in the center comes out clean. Remove from pan using overhang and transfer to a cooling rack. Cool for 5 minutes before slicing with a serrated knife.