Start by making the crust for the apple pie. Add the flour and salt to a large bowl. Then, use a large box grater to grate the cold butter into the flour. Once all the butter is in the bowl, use your hands to rub the butter into the flour until the mix resembles small crumbles.
4 cups flour, 1 1/2 teaspoons salt, 1 1/2 cups cold butter, grated
Add the cold water to the bowl, and mix well. Use your hands to blend the dough until it forms a loose ball. Add a little more water if the mix is too dry or a little more flour if it is too wet.
3/4 cup cold water
Divide the dough into two balls, one a little bit larger than the other. Wrap both balls in plastic wrap. Then, gently pat them both into the shape of a rectangle. It doesn’t need to be perfect, but having the rough rectangle shape will help you roll the dough later.
Refrigerate the dough for 2 hours.
While the dough chills, make the apple pie filling. Add all of the ingredients for the filling to a large bowl, and toss to combine and coat the apples.
8 apples, peeled and sliced, 2 Tablespoons lemon juice, 2/3 cup brown sugar, 3 Tablsepoons cornstarch, 1 teaspoon ground cinnamon, 1/4 teaspoon ground nutmeg, 1/4 teaspoon salt, 2 Tablespoons heavy cream, 2 Tablespoons sugar
Preheat the oven to 375ºF. Cut a piece of parchment paper into a 10x15” rectangle, and put it in the bottom of a 10x15x1 inch baking sheet tray.
Roll the larger rectangle of dough out on a floured surface. Roll the dough into a rectangle that is about 18x13 inches. Place the rectangle into the prepared pan. The dough will hang over the edges of the pan on all sides.
Pour the apple filling and all the juice on top of the dough in the pan. It will seem like a lot, but it will cook down and shrink.
Roll out the second dough into a 16x11 rectangle. Place this dough on top of the apples, covering the whole pan. Seal the edges of the dough, pinching the top crust and the bottom crust together with your fingers.
Brush the top crust with the heavy cream. Then, sprinkle the top with the sugar. Make a few slits in the top of the pie crust to allow steam to escape while the pie bakes.
Bake the slab pie in the oven to bake for 40 minutes. I like to put a second empty tray under the pie on the lower rack in the oven to catch any juices that may bubble over.
The top crust will be golden brown when done, and the pie juices will be bubbling out of the slits in the top crust.
Remove the pie and let it cool for at least 25 minutes before slicing and serving.