Preheat oven to 350 degrees F. Spray a muffin tin with cooking spray (I use coconut oil spray), or set 12 silicone muffin liners on a baking sheet.
Place bananas, old fashioned oats, eggs, almond milk, honey or pure maple syrup, baking soda and vanilla in a blender. Blend until well combined but not completely smooth. You still want to see some small pieces of oats in the batter.
Add the chocolate chips and blend for a few seconds to mix them in.
Divide the batter evenly between 12 muffins cups. I pour the batter directly from my blender, using a small rubber spatula to catch the drips between muffin cups.
Bake for 15-17 minutes, until a tester inserted into the center of a muffin comes out clean. Let cool in the pan for 10 minutes and then carefully transfer to a wire rack to finish cooling. A mini spatula helps to remove the muffins without scratching your muffin tin.
Muffins freeze well. Freeze in a zip-top bag for up to 3 months.