Juicy apples and blueberries baked under a crisp oat-walnut topping made with maple sugar and simple whole-food ingredients. Use fresh or frozen blueberries, with easy gluten-free and dairy-free options.
Place your butter in the freezer for at least 1 hour before starting.
Prepare the filling
Preheat the oven to 360°F (182°C).
Add the chopped apples and blueberries to a 9-inch square baking dish.
Add the arrowroot, maple sugar, lemon juice and cinnamon and toss until evenly coated. Spread the fruit into an even layer.
Make the topping
If you have a food processor: add the cold butter and the flour to the bowl of a food processor and pulse briefly until coarse crumbs form. No food processor? Cut the cold butter into the flour with a pastry cutter, fork or your fingertips, then mix in the remaining ingredients.
Add the rolled oats, walnuts, maple sugar, cinnamon and nutmeg and mix by hand until combined.
Assemble
Scatter the oat-walnut topping loosely and evenly over the fruit.
Bake
Bake for about 35 minutes, or until the topping is golden and the fruit is bubbling around the edges. Frozen blueberries may require another 5–10 minutes.
Cool and Serve
Let the crisp rest for 15–20 minutes before serving so the fruit juices can thicken.Serve warm, at room temperature or chilled.
Notes
Frozen blueberries: Do not thaw before adding them.Gluten-free: Replace the ⅓ cup flour with ⅓ cup 1:1 gluten-free flour blend and use certified gluten-free rolled oats.Dairy-free: Replace the butter 1:1 with a firm dairy-free butter and chill well before using.Nut-free: Omit the walnuts or replace them with pumpkin or sunflower seeds.Sweeter apples: If using very sweet apples, reduce the maple sugar in the filling to taste.Make ahead: Store the prepared filling and topping separately in the refrigerator for up to 2 days and combine immediately before baking.Storage: Refrigerate baked leftovers for up to 3 days.Freezing: Freeze baked or unbaked for up to 3 months. For best topping texture, freeze before baking.