Blueberry Crumble Pie

1 pie crust (homemade or store-bought)
5 cups fresh blueberries
3/4 cup granulated sugar
1/4 cup cornstarch
1 tablespoon lemon juice
1 teaspoon vanilla extract
1/2 cup all-purpose flour
1/2 cup old-fashioned rolled oats
1/2 cup packed brown sugar
1/2 teaspoon ground cinnamon
1/4 teaspoon salt
1/2 cup unsalted butter, chilled and cubed

Preheat your oven to 375°F (190°C).

Fit the pie crust into a 9-inch pie dish, trimming any excess dough around the edges.

In a large bowl, combine the blueberries, granulated sugar, cornstarch, lemon juice, and vanilla extract. Mix gently until the blueberries are evenly coated, then pour the mixture into the prepared pie crust.

In another bowl, mix together the flour, oats, brown sugar, cinnamon, and salt. Add the chilled, cubed butter and use your fingers or a pastry cutter to blend until the mixture resembles coarse crumbs.

Sprinkle the crumble topping evenly over the blueberry filling.

Place the pie on a baking sheet to catch any drips, then bake in the preheated oven for 45-50 minutes, or until the filling is bubbly and the topping is golden brown.

Allow the pie to cool for at least 2 hours before serving to let the filling set.