Carrot Cake Muffins with Walnut Crumble

Name: Carrot Cake Muffins with Walnut Crumble
Prep time: 15 min
Cook time: 40 min
Total time: 40 min
Yield: 8 portions
Ingredients: non-stick spray oil; 120 g rolled oats; 40 g walnuts, shelled, halved; 2 tbsp mixed seeds; ¼ tsp cardamom, ground; ½ tsp cinnamon, ground; 130 g butter, unsalted; 115 g dark brown sugar; 180 g carrots; 50 g all purpose white flour; 2 eggs; ½ tsp baking soda; ½ tsp baking powder; 1 pinch salt