Roll out both Butter Pie Crust rounds to about an 11” circle, ¼”-thick. Transfer 1 piece to a lightly floured Sheet Pan. Invert a Pie Dish and lay on top of the other piece. Use a Paring Knife to trace an outline 1" larger than Pie Dish. Turn Pie Dish right side up and carefully roll dough onto Rolling Pin, then unroll into Pie Dish. Working quickly, gently press dough into bottom of Pie Dish and up sides. Use finger to press dough firmly into bottom edge where base and side meet, letting extra dough hang over edge. Transfer to fridge to chill while you prepare the filling.

Make the brown butter: Melt butter in a medium Stainless Frying Pan over medium heat. Stir butter and swirl the Pan often until butter foams, turns dark brown, and smells very nutty, 5—10 minutes, depending on moisture content of butter. Transfer to a medium bowl and set aside to cool.

Peel and cut apples into ¼”-thick slices. Add apple slices to a large bowl. Taste a small piece of each type of apple together to gauge sweetness

Depending on sweetness of your apples and how sweet you’d like the pie, add between ½–1 cup each granulated and brown sugar. Add salt and taste the apples again. Add lemon zest, juice, flour, cornstarch, cinnamon, and nutmeg to apples. Stir in brown butter. Mix until no streaks of flour or cornstarch remain. Set aside to macerate, 15–30 minutes.

Make the egg wash: Crack egg into a small bowl, add 1 tsp. water, and beat to combine.

Preheat oven to 425F.

Place half of apple mixture into chilled pie crust bottom, reserving any watery juices in bowl. Turn apple slices so the round, peeled sides face outwards towards crust. Add remaining slices, reserving juices in bowl. Tuck all apples in and press down very hard, as much as they let you, packing as tightly as possible. Make sure no apple points are poking up as they can tear crust.

Brush rim of bottom pie crust with egg wash. Place second pie crust on top, shaping over mound of apples, nice and snug. Trim bottom and top pie crust, leaving about 1” around whole pie. Fold excess dough under itself to make a nice, even rim around outside of the Pie Dish. Use two fingers to crimp as desired. (Imagine a cartoon pie crust crimp.) If you notice dough is deepening in color or getting warm to the touch, chill in fridge for at least 15 minutes before baking.

Brush top of pie crust with egg wash. Sprinkle with sugar if you’d like a little extra sparkle and crunch. Cut a few slits in the top crust to allow steam to escape.

Place pie on a parchment-lined Sheet Pan and bake until the shape has set, 25 minutes. Reduce temperature to 375F and bake until crust is a rich golden brown and juices are thickened and bubbling, 30–45 minutes more. 

Let cool at least 2 hours before slicing (juices will still be runny if sliced same day). For cleanest slice, allow to rest 24 hours at room temperature (loosely covered once cooled).