Preheat the oven to 375 degrees F.
Line a large baking sheet with foil and set aside. This will be placed on the rack below the pie while baking to catch any spills and help with easy clean-up
Place the apple slices in a large bowl, add the sugar, flour, and cinnamon, mix well, and set aside.
Prepare your pie crust. If you are using store-bought pie dough be sure to follow the instructions on the box. Some doughs need to warm up to room temperature before being baked.
Stir the apple mixture, and set aside again.
On a lightly floured surface roll out your bottom crust. You want it to be big enough to cover the whole pie dish. An easy way to see if your crust is big enough is to flip your pie dish upside-down and set it on the crust. There should be a ring of dough roughly an inch wide around the pie pan.
Carefully pick up the crust using the rolling pin and place it in the pie dish. Gently press the dough down until it is touching the bottom of the dish. Stir the apple mixture one last time, there should be juice in the bowl and the apples should be coated in the sugary ''sauce'' that has been created.
Carefully pour the apple mixture into the prepared pie dish, and level it out as best you can with the back of the spoon you were using for mixing.
Roll out the top crust, the same as you did the bottom crust. Carefully pick it up using the rolling pin and gently lay it over the apple filling. Trim the crust if needed, you only want to have an inch on overhang at the most. Crimp the edges, then using a fork, poke a few holes in the top of the pie. Or using a sharp knife, cut 3-4 slits in the top of the pie.
Brush on the egg wash if using one, and sprinkle the top of the pie with sugar.
Cover the edge of the pie with foil or a silicone pie shield. Place it in the preheated oven. Place your foil-lined baking sheet on the bottom rack below the pie. Bake for 25 minutes, then remove the foil or silicone pie shield from the edges of the pie. Continue baking for another 20-25 minutes or until the top of the pie is golden brown and the filling is bubbly. Remove the pie from the oven and allow it to cool for 15 minutes before serving.
Serve with a slice of cheese, a scoop of vanilla ice cream, or on its own. Enjoy!