Prepare your pie curst according to the recipe you are using. Refrigerate for at least 30 minutes.
Roll and plate your pie crust before making the pie filling. Return plated pie to the refrigerator while you make the filling.
Preheat oven to 375
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.
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 on center rack of oven for 40 minutes until juices bubble. Cool overnight or for at least 4-6 hours.