1. Preheat the oven to 180°C, grease or line a 12 cup muffin tray.
2. Combine all ingredients in a large bowl, stir until mixed.
3. Spoon the mixture into the prepared muffin tin and sprinkle over the remaining 20g of walnuts.
4. Bake for 15-20 minutes until the muffins are well risen and a skewer comes out clean.
5. Allow to cool slightly before removing from the tin.
6. Once completely cooled, store in an airtight container.