Lightly flour a work surface. Roll out the dough into a circle about 1/8-inch thick.
Transfer the dough to a 9-inch pie plate. Trim and crimp the edges as desired. Place the pie plate in the refrigerator while you make the filling.
Combine the flour, brown sugar, salt, and cinnamon in a large bowl.
Add the butter, and mix using a pastry blender, a fork, or your fingers until thoroughly combined and the mixture forms crumbs. Mix in the oats.
Refrigerate the topping while you make the filling.
To make the filling:
Preheat oven to 375°F (190°C).
Combine the apples, brown sugar, cornstarch, salt, and spices.
Melt the butter in a large skillet over medium heat. Add the apple mixture, and cook, stirring frequently, until the sugar melts and becomes bubbly. Continue cooking about 5 minutes, or until thickened.
Transfer the apples to the chilled pie crust. Sprinkle the crumb topping over the apples.
Place the pie plate on a lined, rimmed baking sheet to catch any potential spills. Bake 45 to 50 minutes, or until the crust and topping are golden brown, and the filling is bubbly.
Notes
*Feel free to substitute your favorite pie crust recipe or use a store-bought crust if you prefer.
Store in an airtight container at room temperature up to 2 days or in the refrigerator up to 5 days.