In a large bowl combine the spelt flours, walnut meal, chopped walnuts, baking powder and spices. Stir well and set aside.
In a large jug combine the wet ingredients and using a fork whisk well until incorporated.
Add the wet ingredients to the dry ones and stir until just combined. Spoon the muffin batter into the muffin cases, filling them close to the top. Combine the crumble ingredients in a food processor until the mixture resembles fine crumbs. Divide the crumble mixture and sprinkle on top of muffins.
Bake for approx. 20 mins until a skewer inserted comes out clean. Allow to cool for 10 mins before tucking in.
If you don't have any spelt flour on hand, you can substitute regular flour.