In a large mixing bowl, whisk together 2 1/4 cups all-purpose flour and 1 tsp salt.

Add the 1 cup of cold, cubed unsalted butter. Using a pastry blender or two knives, cut the butter into the flour until the mixture resembles coarse meal with some pea-sized butter pieces remaining.

Gradually add 1/2 cup ice water, 1 tablespoon at a time, mixing lightly with a fork until the dough just comes together. Be careful not to overmix, as this can make the crust tough.

Gather the dough, form it into a disc, wrap tightly in plastic wrap, and refrigerate for at least 30 minutes (or up to 2 days) to allow the gluten to relax.

In a very large bowl, combine the peeled, cored, and sliced apples, 1/2 cup granulated sugar, 1/4 cup packed light brown sugar, 3 tbsp all-purpose flour, 1 1/2 tsp ground cinnamon, 1/2 tsp ground nutmeg, 1/4 tsp ground ginger, 1 tbsp fresh lemon juice, and 1 tsp vanilla extract. Toss gently until the apples are evenly coated. Set aside.

In a medium bowl, whisk together 3/4 cup rolled oats, 1/2 cup all-purpose flour, 1/2 cup packed light brown sugar, 1 tsp ground cinnamon, and 1/4 tsp salt.

Add the 1/2 cup cold, cubed unsalted butter. Using a pastry blender or your fingertips, cut the butter into the dry ingredients until coarse crumbs form. Avoid overworking; some larger clumps are desirable for texture. Place in the refrigerator until ready to use.

Preheat your oven to 425°F (220°C).

On a lightly floured surface, roll out the chilled pie dough into a 12-inch circle. Carefully transfer the dough to a 9-inch pie dish. Trim the excess dough and crimp the edges as desired.

Pour the apple filling into the pie crust, mounding it slightly in the center. Dot the top of the apples with the 2 tablespoons of small butter pieces.

Evenly sprinkle the chilled oat crumble topping over the apples.

Place the pie on a baking sheet to catch any potential drips during baking. Bake for 15 minutes at 425°F (220°C).

Reduce oven temperature to 375°F (190°C) and continue baking for another 50-60 minutes, or until the apples are tender (test by inserting a thin knife through an opening in the crumble) and the crumble is golden brown. If the crumble starts to brown too quickly, you can loosely tent the pie with aluminum foil.

Remove from oven and let the pie cool on a wire rack for at least 2-3 hours before slicing and serving. This allows the filling to set properly, preventing it from being too runny.