Preheat oven to 350°F. Line an 12-cavity muffin pan with liners and lightly spray with cooking spray. Set aside.
Add oats to a high-powered blender or food processor and blend until they resemble a fine flour. Set aside. In a large bowl, add the overripe bananas and beat with hand mixers until smooth and the consistency of thick applesauce. Measure out exactly 1 level cup and discard any extra.
Add the mashed banana, peanut butter, honey, eggs, and vanilla to a large bowl. Beat with hand mixers until smooth. Add salt, baking powder, and blended oats. Beat again until smooth, scraping down the sides as needed. Add both chocolate chips and gently fold into the batter with a spatula.
Divide batter evenly among the 12 muffin cavities, filling each nearly to the top. Bake for 18 to 22 minutes, or until the tops lightly spring back when touched and a toothpick inserted into the center comes out clean or with a few moist crumbs.
Remove from the oven and let muffins cool in the pan for 5 minutes. Carefully transfer to a wire rack to cool completely.
Notes
Note 1: Use certified gluten-free oats if needed.Note 2: Use very ripe bananas with lots of brown spots for the best sweetness and flavor. Depending on size, you'll need about 2 to 3 large bananas.Note 3: For truly refined sugar-free muffins, use refined sugar-free chocolate chips.Check doneness: The tops should look set and lightly spring back when touched. A toothpick should come out clean or with a few moist crumbs. These continue to firm up as they cool.Storage: Store leftover muffins in an airtight container at room temperature for 1-2 days or in the fridge for up to 1 week. Freeze for longer storage.