Preheat oven to 350F. Grease a loaf pan with some butter / oil and set aside.
Sift the flour, cocoa, baking powder, baking soda and salt to a medium mixing bowl.
Mix together the mashed banana, sugar, molasses, melted butter, eggs and sour cream in a large mixing bowl.
Add the espresso powder, vanilla, ¾ cup chocolate chips and the dry ingredients mix to this. Stir until just mixed. Do not over mix.
Pour the batter into the loaf pan, top with the rest of the chocolate chips and bake for 50-55 mins or until a toothpick when inserted comes clean. Pay attention to the toothpick - if it is just melted chocolate on it, you are fine :)
Remove pan from oven and cool on a cooling rack for 10 mins. Run a knife along the edges of the pan and gently tip over the cake onto the cooking rack. Carefully, invert the cake immediately to right side up, as you dont want to squish the melted chocolate chips on top. Cut and serve warm.