Preheat the oven: Set to 350°F (175°C). Lightly grease a 9-inch square baking dish or a 2-quart casserole.

Prep the berries: In a large bowl, combine 6 cups berries with 2–3 tablespoons maple syrup or sugar, 1–2 tablespoons cornstarch or arrowroot, 1 tablespoon lemon juice, and 1 teaspoon lemon zest. Gently toss to coat. Adjust sweetener based on how tart your berries are.

Make the topping: In a separate bowl, mix 1 1/2 cups almond flour, 1/2 cup gluten-free oats (or more almond flour if skipping oats), 1/3 cup brown sugar, 1/2 cup sliced almonds, 1/2 teaspoon cinnamon, and a pinch of salt.

Add fat and vanilla: Pour in 6 tablespoons melted butter (or coconut oil) and 1 teaspoon vanilla. Stir until the mixture forms moist crumbles that hold when pressed.

Assemble: Spread the berry mixture evenly in the baking dish. Sprinkle the crumble topping over the berries, breaking it into small clumps for an even layer.

Bake: Place on the center rack and bake 35–45 minutes, until the berries are bubbling around the edges and the topping is golden brown. If using frozen berries, it may need an extra 5–10 minutes.

Cool slightly: Let the crisp rest for 10–15 minutes. This helps the juices thicken so each scoop holds together.

Serve: Enjoy warm with vanilla ice cream, whipped cream, or Greek yogurt.