Preheat oven to 350 degrees. Spray a 9x13 inch baking dish with nonstick spray; set aside.
Place a large bowl in refrigerator to chill for 30 minutes. Sift flour, salt and sugar into chilled bowl and add butter and shortening, working into the flour mixture with fingers until large crumbs form, leaving chunks of butter and shortening in flour mixture. Don’t overwork. Add the water, 1 Tablespoon at a time, until the dough holds together. Form into two balls and wrap each in plastic wrap. Refrigerate for 30 minutes while making the filling.
To make the filling, peel, pit and slice peaches. In a large saucepan, melt the butter on medium heat. Add the peaches. In a medium bowl, mix the sugar, brown sugar, cinnamon and cornstarch together with a whisk; Add to the peaches and mix to combine. Cook on medium heat, stirring occasionally, for 5 minutes. Remove from heat and add vanilla; Stir.
Remove dough from refrigerator and roll out one ball into a large circle, cutting to fit on bottom and halfway up sides of the baking dish. Pour filling over crust. Roll out second ball and cut into 1 inch strips or wider. Weave together or leave top crust whole, cutting to fit top, and cut slits in the top. Brush top with melted butter. Combine sugar and cinnamon and sprinkle on top. Bake for 45-60 minutes, until top is golden. Let set for 10 minutes before serving.