Step 1Heat the oven to 350 degrees. Grease a 2-quart casserole dish.
Step 2Peel the apples if desired, then core and thinly slice them. Place in the gratin dish and drizzle over the honey and apple juice.
Step 3In a separate bowl, whisk together the flour, sugar, walnuts, oats, cinnamon and nutmeg. Using a pastry cutter, knives or a fork, cut in the butter until it is reduced to pea-sized pieces in the mixture to form the crumble topping. Sprinkle the topping over the apples.
Step 4Place the crisp in the oven and bake until the apples are bubbling and the topping is golden-brown, about 1 hour. Cool slightly before serving.