Place a rack in the center of your oven and preheat the oven to 350 degrees F. Line a 9 x 5-inch loaf pan with parchment paper so that two opposite sides of the paper overhang like handles. Coat the pan and paper with nonstick spray.
In a large mixing bowl, mash the bananas until very smooth (a hand mixer is a nice shortcut). Double check that you have 1 ½ cups and if not, adjust accordingly. Whisk in the eggs, maple syrup, oil, and vanilla until smoothly combined. Sprinkle the baking powder, baking soda, cinnamon, and salt over the top. Whisk to combine.
Sprinkle the almond flour and flaxseed over the top. With a rubber spatula, fold the batter, just until the almond flour and flax disappear.
Scrape the batter into the prepared loaf pan and smooth the top. Bake for 20 minutes, then loosely tent the pan with foil. Continue baking until a toothpick inserted in the center of the loaf comes out clean and the loaf is very dark golden at the edges and top and a toothpick inserted in the center comes out clean, about 20 to 25 minutes more. Place the pan on a wire rack and let cool in the pan for 10 minutes, then with the parchment paper "handles" gently lift the loaf onto the rack to finish cooling completely before slicing.
For the chocolate drizzle: In a small microwave-safe bowl, place the chocolate chips and coconut oil. Microwave for 30 seconds, then stir. Continue to microwave in 15-second busts, until the chips are almost but not completely melted. Remove from the microwave and stir, letting the residual heat melt the chocolate the rest of the way. Drizzle over the cooled loaf and let the chocolate set a few minutes. Slice and enjoy!
TO STORE: Place bread in an airtight storage container lined with paper towels, and store at room temperature for up to 3 days or in the refrigerator for up to 5 days.
TO FREEZE: Store leftover bread in an airtight freezer-safe storage container in the freezer for up to 3 months. Let thaw overnight in the refrigerator before serving.
HOW TO MAKE ALMOND FLOUR: Add a slightly heaping 2 1/2 cups blanched slivered almonds to a food processor fitted with a steel blade. Pulse them until finely ground. Be careful not to overblend, or it will become almond butter. Measure, then use as directed.