Combine cranberries, diced apples, cinnamon, vanilla, and sugar in a sauce pot. Mix well and turn the heat on to medium. Keep covered with a lid until cranberries give out juice and start to pop. Take the lid off.
Mix well and cook uncovered until apples soften.
Mix cornstarch and cold juice together and stir it into the sauce pot.
Stir well and cook until thickened.
Take the mixture off heat and cool down to room temperature.
You can refrigerate the filling and keep it covered until ready to use. Filling can be prepared ahead of time.
Preheat oven to 350 and grease a 9 inch deep pie dish.
Place pie crust in the pie dish, gently fitting it in.
Spread cooled apple cranberry filling evenly in the pie shell.
In a medium bowl, combine brown sugar, white granulated sugar, cinnamon, and flour. Mix well until all ingredients are incorporated evenly.
Pour in melted butter and carefully fold it in with a large fork. You will want to be careful so you don’t over-mix. Streusel should look like large crumbs and not paste.
Spread streusel topping over the cranberry pie filling.
Place the pie dish on a baking sheet and bake for 35-38 minutes.
Let the cooked pie rest for 2-3 hours before cutting.