Pre-heat oven to 350°F. Grease a 9-by-5-inch loaf pan with nonstick baking spray and set aside.
In a medium bowl, whisk together the flour, cocoa powder, baking soda, and sea salt. Set aside.
In a large bowl, mash the ripe bananas with a fork. Add the sour cream and melted butter, then stir until combined. Stir in the brown sugar, white sugar, egg, and vanilla extract, until combined and smooth. Don't overmix.
Stir the dry ingredients into the wet ingredients until just combined, don’t overmix. Stir in ¾ cup of the chocolate chips.
Pour batter into prepared pan. Sprinkle the remaining ¼ cup of chocolate chips over the top of the bread. Bake for 50-60 minutes. *Do not overbake - See note.
Remove the pan from the oven and set on a wire cooling rack. Let the bread cool in the pan for 15 minutes. Run a sharp knife around the edges of the bread and carefully remove from the pan. Let the bread cool on the wire cooling rack until cooled or just slightly warm. Cut into slices and serve.