Pre-heat the oven to 200°C/gas mark 6. Place 12 paper muffin cases into a muffin tin. Place 150g of plain flour and 150g of wholemeal flour in a bowl with 2½ tsp of baking powder, a pinch of salt, 50g of brown sugar, 75g of blueberries and 50g of chopped walnuts. Lightly whisk together 1 egg, 225ml of semi-skimmed milk and 50g of melted butter, then stir all this into the dry ingredients, and mix well until everything is blended together. Spoon the mixture into the muffin cases and bake for 25 minutes. Serve each muffin with a 125g pot of Activia Layers Raspberry Yogurt, 1 small glass of orange juice and 1 small banana.