Sour Cream Apple Pie

In a large bowl, whisk together the flour, sugar, ginger, and salt.
Dump the butter in the bowl and, using a pastry blender or 2 knives, cut in the butter until the mixture resembles coarse meal. (Sure, you could instead blitz the ingredients in a food processor until crumbly. But why bother having to clean the blade for so little dough?)
Add 3 tablespoons ice water, toss the mixture with a fork until the water is incorporated, and continue mixing until the dough clumps. If the dough seems dry, continue adding water, 1 teaspoon at a time, until it comes together. Flatten the dough into a disc, cover with plastic wrap, and refrigerate for at least 1 hour.
Position a rack in the lowest part of the oven, slide a baking stone or a heavy baking sheet on top, and crank the temperature to 425°F (218°C). Let the oven heat for at least 30 minutes. You want that stone to be hot.

In a small bowl stir together the flour, nuts, butter, sugar, cinnamon, and salt until well combined. Cover and stash it in the fridge until you’re done rolling out the crust.

When the dough is fully chilled, roll it out to 1/8 inch (3 mm) thickness on a lightly floured surface. Draping the dough on the rolling pin, gently ease it into a deep-dish 9-inch (23-cm) pie plate, and then go wild crimping the edge. Back into the fridge it goes for at least 30 minutes.
☞ TESTER TIP: Using a heatproof glass pie plate lets you check the bottom of the pie crust for doneness without having to cut into the pie.

While the crust is chilling, in a medium bowl, whisk the sour cream, sugar, eggs, flour, vanilla, zest, cinnamon, salt, and nutmeg until smooth.

Carefully layer the apples in the pie plate, as you would a gratin, gently flattening them as you go. Slowly pour the sour-cream mixture over the apples. (Yes, it’s a lot of filling. Use it all.)
Bake the pie directly on the baking stone or baking sheet, without the streusel topping, for 20 minutes.
Remove the pie from the oven and carefully crumble the streusel on top. Slide the pie back onto the baking stone, lower the temperature to 375°F (190°C), and bake until the streusel is deeply golden brown and the middle looks dry, 40 to 60 minutes more. If the topping begins browning too much, loosely cover the pie with foil.
☞ TESTER TIP: If the bottom of the pie looks a little underdone at the end of baking, set the plate directly on the hot oven floor for a few minutes to finish. (Yes, I do mean the floor of the oven.)
Transfer the pie to a wire rack to cool completely. (Completely! This baby will fall apart when warm.) Slice and serve only once it’s reached room temperature. Ideally, let it rest overnight.