Preheat the oven to 400F/200C and line a muffin tin with 8 cupcake liners. Alternatively, grease 8 holes in a muffin tin.
Whisk together the all-purpose flour, whole wheat flour, baking powder, baking soda, sugar and raisins.
Pour in the egg, yogurt and melted butter and stir until the mixture just comes together. Don't over-mix or the muffins will turn out tough.
Evenly divide the mixture between the 8 muffins moulds and bake in the pre-heated oven for 20 minutes, or until a toothpick inserted into the centre comes out clean.
Tip the muffins out of the tin and leave to cool on a wire rack for 5 minutes before serving.
Notes
Recipe adapted from King Arthur FlourThese muffins store really well inside a sealed container in the fridge or at room temperature for up to five days and can be frozen for up to six months.