Make the Pastry:

1. In a large bowl, toss the flour and diced butter together with your hands or a pastry blender until the butter is coated in flour. Holding the pastry blender firmly by the handle, press the blades down through the butter with a rocking motion, rotating the bowl as you go so the butter is cut in evenly. If using your hands, rub the butter into the flour. Aim for mostly pea-sized pieces, with some larger marble-sized chunks for added flakiness.
2. Make a well in the center of the flour mixture and add the sour cream. Use a spatula to mix the sour cream into the flour.
3. Using your hands, knead the dough a few times, just until it comes together into one ball. If the dough seems dry and isn’t coming together, add a tablespoon of water at a time until it does (a kitchen safe spray bottle is helpful here).
4. Transfer the dough to a work surface and shape it into a rough disk. Wrap it tightly in plastic wrap. Using a rolling pin, roll the dough out until it stretches to the edges of the plastic wrap to ensure a tight seal. Refrigerate for at least 2 hours, preferably overnight.

Pre-Cook the Apple Filling and Pie Crust:

1. In a large pot, stir together the apples, lemon juice, brown sugar, granulated sugar, cinnamon, salt, and allspice. Let the apples macerate at room temperature until they have released their juices, about 1 hour.
2. Meanwhile, roll out the pie dough to an 11-inch circle. Fit the pastry into a 9-inch pie plate, making sure to press the pastry into the sides and the bottom. Crimp the edges as desired. Refrigerate the pie crust while you cook the filling.
3. While the crust chills, preheat the oven to 425°F and place oven racks in the lower and middle parts of the oven.
4. Set the pot over medium heat and cook the apples, stirring occasionally so they cook evenly, until softened, about 8 minutes. There should still be some liquid left in the pot, if it has cooked off, add 2 tablespoons of apple cider or water.
5. In a small bowl, whisk together the apple cider and cornstarch to make a slurry. Pour the slurry into the pot and stir to combine. Add the cream and vanilla, and cook, stirring, until the filling has thickened, about 1 minute more.
6. Remove the pot from the heat and let the filling cool slightly while you blind bake the crust. Stirring frequently helps it cool faster.
7. Line the pie shell with a round piece of parchment paper, then add pie weights (or dry rice, beans, or lentils) to fill the pie shell, making sure to push the pie weights to the edges. Bake on the lower rack for 20 minutes, then remove from the oven and remove the parchment and pie weights. Return to the oven and bake for an additional 5 minutes, or until the crust has a matte appearance in the middle. Set aside until ready to use.

Make The Streusel, Assemble and Bake:

1. In a medium pot, melt the butter over medium heat, then remove the pot from the heat. To the pot, add the granulated sugar, brown sugar, vanilla, cinnamon, salt, and flour, and stir until well combined.
2. Transfer the apple filling to the parbaked pie crust. Scatter the streusel topping over the filling, pressing it down lightly as needed to fit it all.
3. Place the pie plate on a rimmed baking sheet and bake on the middle rack until the crumb topping is golden brown and the filling is slightly puffed, about 40 minutes.
4. Transfer the pie to a wire rack to cool for at least 4 hours. Serve at room temperature.