In a mixing bowl, combine flour and sugar. Cut in the cold butter until the mixture resembles coarse crumbs.

Stir in ice water, a tablespoon at a time, until the dough comes together. Form into a disk, wrap in plastic, and refrigerate for 30 minutes.

Roll out the dough on a floured surface and fit it into a 9-inch pie dish. Trim and crimp the edges.

In a bowl, combine blueberries, sugar, cornstarch, lemon juice, and cinnamon. Toss to coat the blueberries evenly.

In a bowl, mix flour, brown sugar, oats, and melted butter until crumbly.

Preheat the oven to 375°F (190°C). Pour the blueberry mixture into the prepared pie crust and sprinkle the crumble topping evenly over the filling.

Bake for 40-45 minutes or until the filling is bubbly and the topping is golden brown. Let cool before serving.