Step 1

Preheat the oven to 350F and grease or line a 12-muffin baking tin.

Step 2

Add the oat flour, cacao powder, baking powder, baking soda, and salt to a large bowl. Whisk well, until fully incorporated and no clumps of cacao powder remain.

Step 3

Mash the bananas in a medium-sized bowl, then add in the nut butter, sugar, milk, vanilla, and vinegar. Mix well, until a uniform mixture forms, then pour into the bowl of dry ingredients. Stir everything together – the batter should be relatively thick.

Step 4

Use a scant 1/2 cup to fill each muffin tin 3/4 of the way up. Sprinkle with chocolate chips if desired, then place the muffins in the middle rack of the oven. Bake for 22 to 25 minutes, until the tops have risen and are slightly firm to the touch.

Step 5

Remove the muffins from the oven and let sit in the tin for 5 minutes, then carefully use a butter knife to transfer them to a baking rack and let them cool completely. Serve as desired; store leftovers in an airtight container at room temperature for up to 5 days, or store in the freezer for up to two months.