Prepare the crust according to package directions.
While the crust is chilling:
Combine the sliced apples and lemon juice in a large mixing bowl.
In a small bowl whisk together the sugar, flour, cornstarch, salt and spices. Sprinkle the mixture over the apples and stir to coat them. Stir in the boiled cider or apple juice concentrate and the vanilla. set the filling aside while you prepare the pie crust.
Preheat the oven to 425 degrees F.
Lightly grease a 9" pie pan that is at least 2" deep.
Roll the pie crust into a 13" circle. Transfer into the pie pan.
Crumble topping: In a small bowl mix together the light brown sugar, gluten free flour and nutmeg.
Next mix in the chilled butter and cut with a fork until you have a coarse, crumbly mixture.
Spoon the apple filling into the pan.
Sprinkle your crumble topping all over the top of the pie (use it all).
Place the pie onto a parchment paper lined baking sheet to catch any boilover. Bake the pie for 20 minutes at 425, then reduce the oven temperature to 375 and bake for an additional 40 minutes.
Cool the pie before slicing. Cutting any fruit pie that is still warm is messy.