Preheat the oven: Set to 350°F (175°C).
Lightly grease an 8x8-inch baking dish or similar.
Mix the berries: In a bowl, combine blueberries, 1/3 cup sweetener, lemon zest, lemon juice, and vanilla. If your berries are very juicy, sprinkle in your chosen thickener and toss to coat.
Layer the cottage cheese: Spread the cottage cheese evenly on the bottom of the baking dish. It should form a thin, creamy layer.
Add the berries: Spoon the blueberry mixture over the cottage cheese, spreading it evenly.
Make the crumble topping: In another bowl, stir together almond flour, chopped nuts, optional coconut, cinnamon, remaining 2 tablespoons sweetener, and a pinch of salt.
Add the cold butter cubes and pinch or rub them into the dry mix with your fingers until it forms coarse crumbs.
Top and bake: Sprinkle the crumble evenly over the blueberries. Bake for 25–30 minutes, or until the topping is golden and the berries are bubbling around the edges.
Rest before serving: Let the crumble sit for 10–15 minutes. This helps the juices thicken and the layers set.
Serve: Enjoy warm as-is, or add a dollop of unsweetened whipped cream or a spoonful of plain Greek yogurt.