Prep the butter: Cut the butter into ¼-inch pieces. Place the butter in the freezer to keep it cold while you mix the rest of your ingredients. 

Make the dough: In a large measuring cup, combine the sourdough discard and water. Stir until the starter is completely dissolved. Place the mixture into the refrigerator to keep it cold.

In a large mixing bowl, whisk together the salt and all purpose flour. Toss the butter to coat the pieces in flour. Cut the butter into the flour by flattening the pieces between your palms or using a pastry cutter. Try to keep the butter pieces larger but to coat them thoroughly in butter. Having large sheets of butter in the dough will make for flakier pastry. 

Make a well in the center of the flour mixture. Add the sourdough starter mixture in the center. Using a wooden spoon or your hand, lightly toss the mixture together until the dough feels properly moistened and begins to stick together in clumps. 

Turn the dough out onto a large piece of plastic wrap. It’s ok if the mixture is slightly crumbly at this point, but it should not feel wet or tacky. Enclose the dough in the plastic wrap and flatten it out into a disc. Refrigerate the dough for 30 minutes to allow the flour to fully hydrate and the butter to cool down.

Laminate the dough: Turn the dough out onto a clean work surface. Using a rolling pin, flatten the dough out into roughly a ¼-inch thick rectangle (you don’t have to be exact here). Using your bench knife, fold the dough into thirds like you’re folding a letter. 

Flatten the dough out once more and complete another fold. Divide the dough into two portions and form them into discs.

Refrigerate dough: Wrap the discs in plastic wrap and refrigerate them while you create your filling. Refrigerate your dough for at least 1 hour before rolling it out, you can complete this step up to 48 hours before assembling your pie. 

Make the filling: Peel, core and slice the apples thinly. Toss the apples with Imperial Sugar Light Brown Sugar, Imperial Sugar Extra Fine Granulated Pure Cane Sugar, cinnamon, nutmeg and salt. Cover the bowl with a tea towel and set aside for at least 30 minutes, up to an hour. 

Roll out the pie dough: Place one portion of dough on a lightly floured work surface. Dust your rolling pin with a little flour. Begin flattening out the dough with your rolling pin. Place your rolling pin on the middle of the dough and roll away from yourself. Rotate the dough a quarter turn between each roll until the dough is 12 inches in diameter and about ¼-inch thick.  Transfer the pie dough to a 9-inch pie plate. Ease the pie dough into the crust without stretching it too much. Press the crust firmly against the sides and the bottom of the plate. Trim the crust to the edge of the pie plate.

Refrigerate crust:  Cover the dough with plastic wrap and refrigerate while you finish preparing your filling. 

Cook the filling: Using a large colander over a large measuring cup or heat proof bowl, drain the apples for 5 minutes, you should be able to collect 1 cup of juice. Thicken the juices by heating it in the microwave for 5 to 10 minutes or until it has reduced by half.  

Assemble the pie: Take the crust out of the refrigerator and place an even layer of oatmeal on the bottom of the crust. Add the drained apples into the bottom crust, make sure the filling is spread out evenly and there are no large gaps. Pour the reduced juices over the pie and dot with butter. 

Roll out the other portion of pie dough according to the instructions above. Gently drape the top crust over the pie. Tuck the edges of the top crust under the bottom crust. Seal the dough together using your crimp of choice. Place the pie inside the refrigerator.   

Bake the pie: Preheat the oven to 420F. Place the pie on a baking sheet lined with aluminum foil. Brush the top of the pie with egg white and sprinkle with Imperial Sugar Extra Fine Granulated Pure Cane Sugar. Cut slits on top of the crust to allow steam to escape during baking. 

Bake the pie for 35 to 40 minutes or until the crust is golden brown and the apples feel tender, not mushy, when pierced with a paring knife. 

Place your baked pie crust on a wire rack and let it cool completely, at least 3 hours, ideally overnight, before slicing.