Preheat your oven to 375°F (190°C).

Combine flour and cold, diced butter in a large mixing bowl. Blend until it resembles coarse crumbs. Gradually add ice-cold water until a dough forms.

Roll out the dough on a floured surface into a circle about 1/8 inch thick. Transfer to a pie dish and prick the bottom with a fork.

In a medium bowl, combine blueberries, sugar, sour cream, and optional spices. Toss gently to coat the blueberries.

Pour the blueberry filling into the crust, spreading it evenly across.

In another bowl, mix brown sugar, flour, cinnamon, nutmeg, and melted butter until crumbly. Sprinkle over the blueberry filling.

Bake for 50-55 minutes or until the filling is bubbling and the topping is golden brown.

Let the pie cool for at least 30 minutes before serving to set the filling.