Preheat your oven to 400°F and grease an 8×8-inch baking dish.
**Make the Filling:** Combine apples, apple cider vinegar, and water in a saucepan. Simmer on low heat, covered, stirring occasionally for 15 minutes. Then, add cinnamon, ginger, nutmeg, and salt. Stir until the apples are tender and the juices are thick.
**Make the Topping:** In a food processor, mix flours, oats, walnuts, sugar, coconut oil, cinnamon, and salt until crumbly. Add water if needed.
Scoop the spiced apples into the baking dish and sprinkle with the topping.
Bake for 18 to 22 minutes or until the top is lightly crisp.
Enjoy your easy and delicious apple crumble!