In a large bowl, whisk pumpkin, maple syrup, brown sugar, eggs, milk, vanilla, pumpkin pie spice, and salt until smooth. Set aside.
Preheat oven to 375F. Remove pastry dough from refrigerator and divide into fourths. Return 1/4 of dough to fridge to keep cold for fall cutouts and turn remaining 3/4 of dough onto a floured surface. Roll dough out into a 11x16 inch rectangle then carefully transfer dough to a 10x15 sheet pan.
Fold overhang dough underneath edges so crust goes all the way to top of pan and crimp edges with your fingers. Chill crust in refrigerator an additional 30 minutes or 15 minutes in the freezer.
Turn remaining 1/4 of dough out onto a floured surface and roll out to 1/8-thickness. Use leaf or pumpkin cookie cutters to cut out small cutouts. Transfer cutouts to a medium parchment paper-lined baking sheet and chill in refrigerator until ready to use.
Brush edges of crust well with egg/water wash. (save the rest of the egg wash for later) Pour pumpkin filling into crust and bake pumpkin pie at 375F 45-50 minutes until crust is golden brown and a knife inserted in center comes out clean.
Remove cutouts from refrigerator and brush with remaining egg wash. Bake cutouts at 375F 15-20 minutes until a light golden brown.
Transfer pan to a wire cooling rack and allow to cool completely. Once cooled, transfer to fridge until ready to serve. Garnish pie with cutouts, slice into squares, and serve with whipped cream if desired. Enjoy!