- Filling:
- 6 cups chopped apples
- 2 cups raspberries
- 2 tablespoons white sugar, or to taste
- 1 tablespoon lemon juice
- 1 tablespoon all-purpose flour
- 1 teaspoon ground cinnamon
- Topping:
- 1 cup all-purpose flour
- 1/2 cup oats
- 1/4 cup brown sugar
- 3 tablespoons butter
- 2 tablespoons whole wheat flour
- 2 tablespoons ground flax seeds (optional)
- 2 tablespoons milk
- 2 tablespoons yogurt
- 1 teaspoon baking powder
- 1 teaspoon ground cinnamon
- 1/4 teaspoon salt
- 1/8 teaspoon baking soda
- Preheat oven to 425 degrees F (220 degrees C).
- Mix apples, raspberries, white sugar, lemon juice, 1 tablespoon flour, and 1 teaspoon cinnamon together in a bowl; pour into a 9×13-inch baking dish.
- Mix 1 cup flour, oats, brown sugar, butter, whole wheat flour, flax seeds, milk, yogurt, baking powder, 1 teaspoon cinnamon, salt, and baking soda together in a separate bowl until topping is crumbly. Spread topping over apple mixture.
- Bake in the preheated oven until topping is golden brown, 20 to 30 minutes.