Heat oven: 180°C (fan). Line a muffin tin with cases. Alternatively, I would recommend using a silicone muffin tray - it is much easier and less of a faff.
Wet ingredients
Mash bananas: In a bowl, mash the bananas until smooth.
Add eggs, Greek yogurt, oil, honey and mix until combined.
Dry ingredients
Stir in the oat flour, whole oats, baking powder, bicarb, cinnamon and a small pinch of salt.
Divide the mixture between two large bowls. In one bowl, fold through the dark chocolate chips and in the other, add the blueberries.
Spoon the mixture into muffin cases/silicone tray before topping with extra chocolate chips/blueberries.
Bake for 18-20 minutes until golden and a skewer comes out clean.