Preheat your oven to 425 degrees. Spray a 12 X 17 baking sheet with non-stick cooking spray.
Roll out the first pie crust so it covers a third of the baking sheet and overlaps on side. Repeat with remaining pie crusts until the sheet pan is covered. Gently press the dough to fit the pan and trim away any overhang.
Using a fork, prick the bottom of the dough and place into the oven to bake for about 10 to 12 minutes.
Remove the crust from the oven and let it cool slightly. Reduce the oven temperature to 350 degrees.
While the crust cools, make the filling. In a large bowl combine the pumpkin, whipping cream, brown sugar, eggs, all-purpose flour, spices, vanilla and kosher salt.
Pour the filling over the crust and bake for about 40 minutes or until set.
Cool completely before slicing into squares and garnishing with whipped cream and cinnamon.