Preheat oven to 350°F. Mix crumble ingredients together in a large bowl with a spoon or your hands. Mix until it's all incorporated and starts to stick together in chunks. Leave some big and small pieces in the bowl. Set aside.
In another bowl, mix together blueberries, arrowroot powder, cinnamon and nutmeg. Then add the vanilla, honey, and lemon zest.
Pour blueberry mixture into a 9" pie dish. Sprinkle the crumble mixture on top. Bake for about 10 minutes, until the crumble gets brownish, then cover with aluminum foil and bake another 30 minutes. Enjoy.