I start by adding sliced apples to a large bowl. Then I mix in granulated sugar, flour, cinnamon, nutmeg, lemon juice, and vanilla extract until the apples are evenly coated.

Next, I pour the apple mixture into the unbaked pie crust, spreading it out evenly so every slice gets plenty of filling.

In another bowl, I combine brown sugar, oats, chopped pecans, and butter. I use a fork to mix until it forms a crumbly, streusel-like texture.

I sprinkle the pecan streusel generously over the apples, place the pie on a baking sheet, and bake until the topping is golden and the filling is bubbly.

Once baked, I let the pie cool for at least 30 minutes. This helps the filling set and makes slicing much easier.