Crank your oven to 425°F and roll out your pie crust, settling it into a 9-inch pie pan. Trim any overhang to about 1 inch, then fold it under and crimp the edges however makes you happy.
Toss the sliced apples with granulated sugar, flour, cinnamon, nutmeg, and salt in a large bowl. Use your hands to make sure everything gets coated — the flour prevents a soggy bottom and the spices need to reach every slice.
Pile the seasoned apples into your prepared crust, mounding them slightly in the center since they'll cook down. Scatter those 2 tablespoons of butter cubes over the top — they'll melt and create pockets of richness as the pie bakes.
Make your crumb topping by whisking together the flour, brown sugar, and cinnamon. Add the cold butter cubes and work them in with your fingertips or a pastry cutter until you get a mixture that looks like chunky breadcrumbs with some larger butter pieces still visible.
Distribute the crumb topping evenly over the apples, pressing gently so it adheres. Don't pack it down — you want those loose bits that will turn golden and crispy.
Slide the pie into your hot oven for 15 minutes, then drop the temperature to 350°F and continue baking until the topping is deep golden brown and you can see the apple juices bubbling around the edges. The apples should feel tender when poked with a knife.
⏱ 35 min
Let the pie cool completely on a wire rack before slicing — this gives the filling time to set up so it doesn't run all over the plate. The hardest part is waiting, but it's worth it.
⏱ 1 hr