In a large bowl, whisk dry ingredients together and add shortening. Break it up into small pieces and coat with flour. Add cold, cubed butter and cut it into flour mixture until crumbly, like a coarse meal.
Add cold water until it just forms into a dough - be sure to only add water as needed as you don't want the dough to be too wet. Form dough into a ball and cut on half. Press into a disk-like shape, wrap tightly in plastic wrap and chill for 30 minutes in the refrigerator before using.
In another large bowl, whisk both sugars together. Toss gently with sliced peaches to coat and set aside for 1 hour.
During this hour, get your pie crust ready. Grease a pie plate and roll out each disk to be about 10-11". Press one rolled out crust down into the bottom of the pie dish, going up the sides. With the second crust, cut into 1-1 ½" strips for lattice top.
Preheat oven to 425°F.
After 1 hour, peaches will be sitting in a bowl of juice. In a small bowl, combine corn starch, spices and water until smooth. Separate the peaches and juice and pour the juice in with the corn starch mixture - set the peaches aside for later.
Pour mixture into a small saucepan on low heat and whisk until thickened. Be sure to whisk constantly because it may over-thicken very fast and become gloppy. If this happens don't panic, just whisk furiously and it will smooth out. You want it to be thick enough to coat the back of a spoon and when you slide your finger across, the line should stay for a few seconds.
Stir in butter and lemon juice. Once butter is melted, gently fold in the sliced peaches.
Pour filling into prepared crust and arrange the dough strips into a lattice pattern. Brush the egg white on top of the crust and sprinkle with granulated sugar before placing into oven.
Bake for 10 minutes at 425°F then turn temperature down to 350 degrees for 40-45 minutes. After about 25 minutes, you may notice the edges are starting to brown. If this happens, cover just the edges with foil or a pie shield and bake for the remaining time. Pie is done when the top is very lightly browned and filling is bubbling. While baking, you may notice liquid rises to the top but don't worry, by the time baking is done it will thicken up beautifully.