Remove frozen gluten free pie shell from freezer, and allow to thaw. If using homemade crust, leave pie shell in refrigerator while preparing the rest of the pie.
Cook strawberries and raspberries in a medium pot for 5 minutes, to release juices. Then add sugar and spices. Cook 8-10 minutes more, until it thickens. Allow to completely cool.
In a large bowl, add 1 tbsp lemon juice. Add sliced apples and coat. Add blueberries, rhubarb and cornstarch. Stir until all fruit is evenly coated in cornstarch.
To the large bow, stir in cooled strawberry and raspberry compote with the remainder of the fruit.
Place all the filling in the pie crust. Cover crust with tin foil or pie shield to prevent burning. Leave foil on for the entire baking time.
To make the streusel topping, use food processor or pastry cutter to cut butter into flour. Add brown sugar. Top uncooked pie with streusel. It may seem like a lot of topping, but you're going to need it all.
Place cookie sheet in oven, and preheat to 400°.
Once oven has reached 400°, place pie on cookie sheet and bake at 400° for 20 minutes. Then turn down oven to 350°. and then bake for another 35 minutes.
Remove pie from oven and allow to cool for at least 4 hours before serving.