1. Preheat the oven to 200°C/400°F/Gas Mark 6. Place 6 muffin paper cases into a muffin tin.
2. Melt the butter over a low heat, and set aside to cool slightly.
3. Peel and core the apples, and chop into cubes about 1cm.
4. Sieve the wholegrain and white spelt flour, baking powder, cinnamon and salt together into a mixing bowl. Add the sugar, apples and sultanas into the flour mixture.
5. In a jug, mix together the milk, egg and melted butter. Pour the liquid over the dry ingredients and mix together until combined.
6. Divide the mixture equally between the six paper muffin cases.
7. Make the streusel topping – rub the butter, wholegrain spelt flour and cinnamon together to create a chunky breadcrumb mixture, do not over rub, keep the butter in slightly larger pieces than you would for pastry.
8. Add the muscovado sugar and chopped hazelnuts to the breadcrumb mixture. Stir to combine.
9. Divide the streusel topping evenly over the six muffins, don’t press into the muffin mixture, leave it loose and pile it high!
10. Bake in the oven for 20-25 minutes, until the streusel topping is golden brown and the muffins have risen.
TIP: This recipe is really easy to adapt, change the apples for pears, and swap the cinnamon for a different spice such as ginger, all spice or even star anise!  Chopped almonds in the streusel would also give a lovely alternative favour too!