Peel apples and cut them into small pieces. Grind walnuts into fine crumbs.
Put your apples into the casserole dish and sprinkle 2 teaspoons of cinnamon on top with some brown sugar or agave syrup. Mix everything well.
Melt butter and mix with flour, oats, 2 teaspoons cinnamon, walnuts, and agave syrup.
Knead your mixture into crumbles. Spread your crumbles over apple pieces.
Now place the Apple Crumble in the oven at 180° for 20 minutes.