Heat the oven: Set to 350°F (175°C). Line a 9x5-inch loaf pan with parchment and lightly grease the sides.

Make oat flour: Add rolled oats to a blender and blend to a fine flour. You’ll need about 2 cups oat flour total (start with 2 1/4 cups oats).

Mix dry ingredients: In a large bowl, whisk 1 1/2 cups oat flour, 1 cup almond flour, 1 1/2 teaspoons baking powder, 1/2 teaspoon baking soda, 1/2 teaspoon salt, and 1 teaspoon cinnamon. Reserve remaining oat flour if batter looks thin later.

Mash bananas: In another bowl, mash 3 ripe bananas until mostly smooth. You want about 1 1/4 to 1 1/2 cups mashed.

Whisk wet ingredients: To the bananas, add 2 large eggs, 1/4 cup maple syrup or honey, 1/4 cup oil, and 2 teaspoons vanilla. Whisk until glossy and well combined.

Combine: Pour wet ingredients into dry. Stir with a spatula until just combined. If the batter looks very loose, sprinkle in 2–4 tablespoons more oat flour. It should be thick but scoopable.

Fold in the good stuff: Gently fold in 3/4 cup chocolate chips and 1/2 cup chopped nuts if using. Don’t overmix.

Pan and top: Scoop into the prepared pan. Smooth the top. Sprinkle a few extra chocolate chips and oats on top for a pretty finish.

Bake: Bake 50–60 minutes, or until a toothpick comes out with a few moist crumbs (melted chocolate is fine). If the top browns too fast, tent loosely with foil for the last 10–15 minutes.

Cool completely: Let cool in the pan 10 minutes, then lift out to a rack. Cool at least 45 minutes before slicing so it sets and stays moist.