Step 1

In a large mixing bowl and using a pastry blender (or two forks), mix together the flour, salt, cold cubed butter, and cold vegetable shortening until you have small pea-size pieces. Some larger pea-size pieces are fine too! You can use a knife to clear out the pastry blender if it gets clogged as you mix everything together.

Step 2

Add in the ice cold water 1 tablespoon at a time, and using a spatula or your hands, mix together until the pie dough can form a ball and it is no longer crumbly. If there are any crumbly bits, just add the tiniest bit of cold water so they blend in with the rest of the dough.

Step 3

After forming the ball of pie dough, place it on a lightly-floured, clean surface and pat it into a 1"-1 1/2" thick disc. Then double wrap tightly in plastic wrap and place in the coldest part of your refrigerator (usually the back) for a minimum of 1 hour or overnight (preferred).

Step 4

In a medium bowl and using a pastry cutter (or two forks), blend together the all-purpose flour, light brown sugar, old fashioned oats, and cold unsalted cubed butter until the crumble mixture forms. Set aside.

Step 5

Adjust the oven rack to the 2nd level position and preheat the oven to 425ºF.

Step 6

On a well-floured, clean surface, roll out the pie dough disc you made earlier (or unroll if using store-bought) and carefully place into the 10" skillet. Trim and/or fold in any excess pie dough, then place it back in the refrigerator as you make the peach pie pie filling.

Step 7

In a large bowl, mix together the sliced peaches, light brown sugar, granulated sugar, corn starch, vanilla extract, lemon juice, and cubed pieces of butter until well coated. The mixture will start to become juicy—that's okay!

Step 8

Take out the pie plate out from the refrigerator and carefully add in a layer of peach pie filling using a slotted spoon to drain the excess juices. Then top with a layer of the brown sugar crumble. Repeat again until you've used up both the pie filling and the crumble.

Step 9

Optional step - using a pastry brush, lightly brush the egg white along the pie crust edges. You won't need to use all it—just a little coverage will be good.

Step 10

Place the pie in the oven and bake for 15 minutes at 425ºF. Optionally, you can place a jelly roll pan on the oven rack below the pie to catch any possible run-off juices.

Step 11

After 15 minutes, decrease the oven temperature to 375ºF and bake for an additional 40-45 minutes. At this time, if you'd like to, you can add a pie crust shield to avoid burning your pie crust edges. You can use something like the one I just bought or you can simply use pieces of aluminum foil to place around the edges.

Step 12

Once done, remove the skillet from oven and allow to cool completely.