Preheat the oven to 325°F degrees. Line a 12-cup muffin pan with muffin liners.
Peel bananas and add to a large mixing bowl. Using a sturdy whisk or fork, mash bananas until smooth. Add the oil, sugar, maple syrup, flax eggs, milk and vanilla. Whisk until well incorporated.
Add oat flour, oats, baking powder, baking soda and cinnamon. Whisk together until just incorporated, making sure no flour patches remain. Fold in chocolate chips.
Using a large scoop, scoop and drop batter evenly into muffin cups. I use this ice cream scoop for easy scooping and a beautiful round top. If not using the scoop, smooth batter into an even layer, with a domed top (rise) in the center. Optionally, press oats and chocolate chips on top of the muffins.
Bake for 24-30 minutes. Mine took 29 minutes for large domed-topped muffins.
- Storage notes: Store in an airtight container for up to 1 week. - Freezing instructions: Cool completely and store in an airtight, freezer-friendly container or bag. Keep for 1-2 months. Allow to thaw at room temperature for 10-40 mins, or heat in the microwave in 10-second increments until just warm.