Preheat the oven to 350 degrees F. Grease and flour one 9×5 inch loaf pan.
In a medium bowl, stir together the bananas, sugars, butter, milk, and egg; set aside.
In another medium bowl, whisk together the flour, instant espresso powder, baking soda and salt. Make a well in the middle of the dry ingredients. Pour the wet ingredients into the well and stir just until combined. Fold in the chocolate chips.
Scrape batter into prepared loaf pan and smooth surface with a rubber spatula. Bake in preheated oven for 55-60 minutes, until a toothpick inserted in the center of the loaf comes out clean. Cool in pan 10 minutes, then transfer to wire rack and cool completely before serving, at least 1 hour.