For the pan:
Lightly butter and flour a 6" x 2¾” deep springform pan and line with one recipe of pie pastry. (See recipe index for pie pastry inspiration.) One recipe for a 9” single crust pie pastry will fit a 6” x 2¾” springform pan.
Line the bottom and then the sides of the pan evenly with the dough leaving a ½” overhang of dough; turn this under to create an edge around the top; crimp decoratively. Freeze until firm then line with parchment or foil and beans (or pie weights) and bake at 400 degrees F for 20 minutes. Carefully remove the parchment and beans, dock the dough with a fork to prevent it from puffing up, and bake the shell an additional 10-15 until dry. (It should be well baked to prevent a soggy bottom and sides.) Set aside to cool while you prepare the crumb and filling. (This can also be made in a traditional 9" pie plate; not a deep dish.)
For the crumb- (makes enough for one 9” pie)
1 cup fine cornmeal
½ cup all-purpose flour
⅓ cup packed light brown sugar
¼ teaspoon ginger
½ teaspoon kosher salt
7 tablespoons cold, unsalted butter, cut into pieces
¾ cup walnut halves and pieces
Combine the cornmeal, flour, brown sugar, ginger, and salt in the bowl of a stand mixer fitted with the paddle attachment. Add the cold butter pieces and the walnuts and mix on low speed until the mixture is crumbly with small chunks of butter remaining. Store in a tightly sealed container and refrigerate for at least one hour before using.
(The crumb will keep, covered and refrigerated for up to 1 week or frozen for up to 1 month.)
Preheat the oven to 400 degrees F.
For the filling-
1½ pounds peeled, cored, thinly sliced apples (preferably a combination of Macoun, Winesap, and Pippin)
2 teaspoons lemon juice
¼ cup granulated sugar
2 tablespoons tapioca starch
½ teaspoons ground cinnamon
⅛ teaspoon freshly ground nutmeg
¼ teaspoon salt
2-3 tablespoons maple syrup, depending on tartness of apples
2 tablespoons unsalted butter, cut into small cubes
In a large bowl, combine sliced apples with lemon juice; toss to coat. In a small bowl, whisk together sugar, tapioca starch, cinnamon, nutmeg, and salt. Let the apple slices macerate for half an hour; set the apples and their juices in a large colander. Strain the apples and transfer all of the juices to a small saucepan. (Return the apples to the large bowl.) Cook over low heat until the mixture reduces, thickens and becomes syrupy. Remove from the heat, add the maple syrup and butter. Combine thoroughly then add the cooked syrup back to the apples, coating thoroughly. Pour the filling into the pre-baked shell, scraping all of the juices over the apples. Retrieve the crumb from the fridge. Place the pie on a parchment lined baking sheet. Sprinkle the crumb evenly over the apples; do not pack it down.
Bake on the bottom rack at 400 degrees for 20 minutes then reduce oven temperature to 375 degrees F. Bake for an additional 40 minutes, keeping an eye that the crumb isn’t getting too brown- if so, cover it with a sheet of parchment paper. Bake until the filling bubbles around the edges and from the center of the pie. (You can move some of the crumb aside and take a peek.) Apples should be tender but not mushy. Crumb should be deeply golden. Transfer the pie to a cooling rack. Cool for several hours before carefully removing the side of the pan. It is easiest slice this using a serrated knife. Cover and refrigerate any leftovers.