Make the Pie Crust:

In a large bowl, combine the flour and salt. Cut in the cold butter using a pastry cutter or fork until the mixture resembles coarse crumbs. Add the ice water 1 tablespoon at a time, mixing until the dough just comes together. Roll the dough into a ball, wrap it in plastic, and chill in the refrigerator for 30 minutes.

Prepare the Apple Filling:

In a large bowl, combine the sliced apples, granulated sugar, brown sugar, lemon juice, cinnamon, nutmeg, and flour. Stir until the apples are evenly coated. Set aside.

Make the Streusel Topping:

In a separate bowl, mix the flour, oats, brown sugar, and cinnamon. Cut in the cold butter until the mixture forms crumbs. Set aside.

Assemble the Pie:

Preheat the oven to 375°F (190°C). Roll out the chilled pie dough on a lightly floured surface to fit a 9-inch pie pan. Press the dough into the pan and trim any excess. Pour the apple filling into the crust and dot with small pieces of butter. Sprinkle the streusel topping evenly over the apples.

Bake the Pie:

Bake the pie for 45–50 minutes, or until the crust is golden and the filling is bubbly. If the edges of the crust brown too quickly, cover them with foil and continue baking.

Cool and Serve:

Allow the pie to cool for at least 30 minutes before slicing. Serve with a scoop of vanilla ice cream or a dollop of whipped cream for the ultimate indulgence!