Preheat your oven to 350°F. Grease or line the wells of a standard 12-cup muffin tin and set it aside.
In a blender or food processor (See Recipe Notes; it may be necessary to blend the batter in two equal parts), place the bananas, sour cream, eggs, vanilla, sugar, oats, baking powder, baking soda, and salt.
Pulse or blend on high speed until well-blended. (See Recipe Notes)
Add about 3/4 of the chocolate chips to the batter, and mix by hand until evenly distributed throughout.
Divide the batter evenly among the prepared wells of the muffin tin.
Shake the tin back and forth to distribute the batter into an even layer in each well.
Sprinkle the tops evenly with the remaining chips.
Place the muffin tin in the center of the preheated oven and bake for 18 minutes, or until a toothpick inserted in the center of a muffin comes out with a few moist crumbs attached.
Remove from the oven and allow to cool in the baking sheet for 10 minutes before transferring to a wire rack to cool completely.
Serve immediately or wrap tightly in freezer-safe wrap and freeze. Defrost at room temperature before serving.
Video
Notes
About using a blender or food processor.The blender I use most often has only a 24 ounce capacity. That isn't large enough to make the batter for these muffins in one batch. I divide all of the ingredients by half, and make in two batches, but bake them both at the same time in the same muffin tin.If you'd prefer, you can blend the muffins in 2 batches and bake them 6 at a time. If you don't have a 6-cup muffin tin, you can use a 12-cup muffin tin and fill the empty muffin wells with water to ensure even baking. The baking time is the same whether you're making 12 muffins or 6 muffins in the oven at a time.If you don't have a blender or food processor.You can use 1 7/8 cup (225 g) oat flour in place of rolled oats, mash the bananas with the beaten eggs as smoothly as possible, and then mix all of the ingredients together by hand in a large mixing bowl.If you grind your own oat flour, be sure to grind it as finely as possible or the muffins may be a bit grainy (which is not really a problem, to be honest).Nutrition information.Nutrition information is an estimate only from online calculators, provided as a courtesy, and should not be relied on under any circumstances.