Preheat the oven to 375°F.
Grease a 9-inch square pan.
Core the apples and slice them very thin into a large mixing bowl (peeling them is optional).
Sprinkle with lemon juice, sweetener, cinnamon, nutmeg, and orange zest. Add the berries and stir the mixture gently. Sweeten to taste.
Put the apples and berries into the baking dish. They'll be very tall, but dont' worry, they'll cook down.
For the streusel topping, in a small mixing bowl, mix the coconut, cinnamon, sweetener, salt, coconut oil, and chopped nuts. Sprinkle this mixture over the apples and press it in.
Bake for 35-40 minutes, until apples are soft.