Preheat oven to 350 degrees F (175 degrees C). Spray a large baking dish with cooking spray.
Combine apples, white sugar, 3 tablespoons potato starch, lemon juice, and 1 teaspoon cinnamon in a bowl. Pour apple mixture into the prepared dish.
Mix 2 cups potato starch, brown sugar, margarine, and 1 teaspoon cinnamon together in a separate bowl until crumbly but moist. Sprinkle topping over the apple mixture.
Bake in the preheated oven until golden brown on top, 40 to 50 minutes.
