Preheat the oven to 200℃ (180℃ fan)/400°F/gas mark 6. Line a muffin tin with tulip muffin cases.
Place 125g (4oz) wholemeal spelt flour 50g (2oz) plain flour, 2tsp baking powder, ½tsp ground cinnamon, 125g (4oz) muesli, grated zest of ½ orange, 125g (4oz)sugar and 50g (2oz) chocolate chips into a mixing bowl. Stir to combine and make a well in the dry ingredients.
In another bowl or large jug add 150ml (¼pt) milk, 2 eggs and 1 tsp vanilla extract. Use a fork to beat the eggs into the milk. Then beat in 150g (4oz) melted butter.
Pour the egg and milk. mixture into the centre of the dried ingredients and use a spatula or large metal spoon to quickly fold everything together.
Fill the muffin cases about ⅔ – ¾ full with the batter mixture. Sprinkle a little extra muesli, chopped nuts or seeds if desired.
Bake in the centre of the oven for 25 minutes. Once baked, remove from the oven. Allow to stand for a few minutes in the tin before transferring the muffins to a wire rack to cool.