For pastry dough:

1 1/2 cups all-purpose flour

2 T. granulated sugar

3/4 t. salt

1 stick (1/2 cup) plus 2 T. cold unsalted butter

4 to 6 T. ice water

For topping:

6 T. unsalted butter

6 T. firmly packed brown sugar

6 T. all-purpose flour

3/4 c. chopped walnuts

For filling:

3 lbs. golden delicious or jonagold apples (about 6 medium)

1/2 c. firmly packed brown sugar

1/4 c. granulated sugar

2 T. all-purpose flour

1 T. fresh lemon juice

3/4 t. cinnamon

optional: 1 vanilla bean, seeds scraped

2 T. milk

1 T. granulated sugar

To make pastry dough:

In a large bowl with a pastry blender or in a food processor, blend together flour, sugar, salt and butter until mixture resembles coarse meal. Add 2 T. ice water and pulse until incorporated. Add enough remaining water, 1 T. at a time, pulsing until dough comes together. On a work surface, smear dough in 3 or 4 forward motions with heel of hand to slightly develop gluten in flour. Form into a ball and flatten to form 1-inch think disk. Wrap dough in plastic wrap and chill 30 minutes.

To make topping:

Combine butter, brown sugar, and flour in a bowl with a pastry blender or in a food processor until mixture resembles coarse meal. If mixture is too wet, add a bit of flour. Toss with chopped walnuts to combine. Chill topping, covered until ready to use.

To make filling:

Toss brown sugar through vanilla in a large bowl. Peel and core apples. Cut apples into 1/2-inch thick wedges. Toss apples with sugar mixture.

Preheat oven to 350F.

On a lightly floured surface, roll out dough into a 14-inch round (about 1/8-inch thick). Transfer dough round to a deep-dish pie dish, easing to fit and letting dough overhang rim. Spoon filling into shell. Fold edges of dough into pie to form crust. Bake pie in middle of oven for 1 hour. Remove pie from oven.

Break up any large chunks of topping. Brush crust with milk and sprinkle with sugar. Crumble topping onto pie filling evenly. (If crust is turning too dark, cover edges with foil at this point.)

Return pie to oven and bake for 30 more minutes or until filling is bubbling and topping is golden. Cool pie on a rack.