Blueberry Icebox Pie

Crust:
1 1/3 cups graham cracker crumbs (11 whole crackers)
5 tablespoons melted unsalted butter
1/2 cup old-fashioned rolled oats (not the quick-cooking kind)
3 tablespoons firmly packed brown sugar
1 teaspoon pure vanilla extract
Generous pinch of salt

Filling:
1/4 cup cornstarch
1/4 cup water
5 cups fresh blueberries, divided
2/3 cup sugar
1/2 teaspoon ground cinnamon
1/4 teaspoon ground nutmeg
1 tablespoon unsalted butter

Prepare the crust: Preheat the oven to 350 degrees. In a food processor, grind together the graham cracker crumbs, butter, oats, brown sugar, vanilla and salt until moistened, about 30 seconds. Press crust mixture evenly across the bottom of a 9-inch pie plate and all the way up the sides of the pan, packing it tightly with your fingertips so it is even and compacted. Bake the crust at 350 degrees until crisp, 6 to 8 minutes. Let it cool completely before filling it.

Prepare the filling: In a small bowl, combine cornstarch and water and stir mixture until completely smooth. Combine 3 cups of blueberries, sugar, cinnamon and nutmeg in a medium saucepan. Bring the mixture to a boil, stirring occasionally. Stir in the cornstarch mixture and cook over medium heat, stirring constantly, until it thickens. Cook an additional 2 minutes. Remove from heat and stir in the butter and remaining blueberries.
Scrape filling into prepared crust and cover with plastic wrap. Refrigerate until filling is completely set, at least 6 hours and up to 1 day. Serve chilled.