Prepare your pie crust according to the recipe you are using. Refrigerate for at least 30 minutes.
Roll and plate your pie crust before making the pie filling. Cover the pie and return to the refrigerator while you make the filling.
Preheat oven to 425
Prepare oatmeal crumb topping by placing all dry ingredients in a food processor. Mix well, then add the butter and pulse until well incorporated. Turn out into a bowl and using your hands, form into crumbs. Set aside.
Peel and grate apples. Use a small strainer or even a paper towel to squeeze liquid from the grated apple if necessary.
Combine blueberries, grated apple, sugar, orange zest, orange juice and vanilla in a medium bowl.
In a small bowl or ramekin, combine cornstarch, reserved 2T of sugar and nutmeg.
Add cornstarch mixture to blueberries and gently mix.
Turn out into pie shell and top with oatmeal crumb topping.
Bake at 425 on lower rack of oven for 15 minutes. Reduce oven temperature to 350 and bake for another 30 minutes or until juices bubble. Cool overnight or for at least 4-6 hours.