Optional: add the oats to the blender and pulse a few times - this makes the oats more like flour and creates a softer muffin but this step is totally optional.
Add all ingredients to the blender, pulse a few times and then blend on low speed until ingredients are all incorporated. This will take 45 - 60 seconds. Stop the blender as needed to scrap the mixture down so that it all mixes in.
Pour the batter into a muffin tin lined with 12 paper cases. Sprinkle chocolate chips on top of the batter if using.
Bake for 15-17 minutes until a toothpick inserted in the centre comes out clean.
Cool in the tin for 5 minutes, then transfer to a cooling rack.
Store in an airtight container for a week or freeze.