Preheat oven to 350°F.
Combine all the dry ingredients in one bowl. (If making your own oat flour, simply process 1 cup of oats in a food processor or blender under a flour consistency has formed).
Melt the coconut oil, let it cool before adding it to the wet ingredients.
Mash the banana, then add the rest of the wet ingredients together in a bowl.
Add the wet ingredients to the dry ingredients.
Place into lined muffin tins or grease the muffin tray (should make 8-12 muffins). Fill 3/4 of the way.
Bake for 23-25 minutes, run a toothpick through them to check they are cooked all the way through.
Let cool for 10 minutes in the muffin tins, then transfer to a cooling rack and let cool for 10 minutes before diving in!