Preheat oven to 375 degrees F.
Combine oat flour, oats, baking powder, baking soda, salt and brown sugar and mix well. Set aside.
In a food processor or a bowl with an electric mixer, puree or mix your ripe banana until relatively smooth. Add in yogurt and mix until well combined. Add in softened butter and vanilla, mix until well combined. Add in eggs, mixing until combined.
Combine wet and dry ingredients in a large bowl. Add in milk and stir until all ingredients are well combined but do not over mix. Stir in chocolate chips.
Scoop into a greased muffin tin.
Bake for approximately 15-20 minutes or until toothpick inserted into center comes out clean and/or top of muffins springs back when lightly touched. Cool. Store covered. Once cool, you can store them in the freezer, I simply place mine into a zipper style freezer bag.