Add all pie filling ingredients to pot and mix well.
Cook over medium heat, stirring frequently, until thickened.
Pour pie filling into pie shell and set aside.
Make meringue by whipping egg whites and cream of tartar with mixer, adding a couple of TBSP sugar at a time until stiff peaks form.
Spoon meringue out on top of pie filling and spread to edges. Use your spoon to form peaks on top of meringue.
Bake pie at 325º for 25-30 minutes, or until golden brown.
Remove from oven and allow pie to come to room temperature before serving or moving to refrigerator.
If you immediately move your pie from the oven to the refrigerator, your meringue will "weep", so it's best to leave the pie out of the oven until the temperature has come down. Ideally, let it rest on a cooling rack so air can circulate underneath