To make the crust:
Place flour, butter sugar, and salt into a large food processor.
Pulse until coarse crumbs form.
Add water 1 tablespoon at a time until a ball of dough forms.
Shape into a disc and wrap in plastic wrap.
Refrigerate for at least 30 minutes. The dough can be made up to 2 days in advance.
To make the pumpkin pie:
Preheat oven to 375 degrees F.
Combine all pie ingredients in a large bowl and beat until well combined with electric mixer.
Press crust dough into the bottom of a 9x13” baking dish that has been sprayed with cooking spray. *Note: I removed about ½ cup of the dough to roll out and make cut out leaves for decoration on top of the bars. I added them to the edge of the pan 30 minutes into the baking time, so they did not sink into the filling. You can skip this part and still use all of the dough for the crust, it will just be slightly thicker.
Bake in preheated oven for 15 minutes.
Pour pie mixture over baked crust.
Bake another 50-60 minutes, until edges are set and filling is firm. Let cool completely and refrigerate until ready to serve.
To make maple whipped cream:
Place heavy cream and maple syrup in a large bowl with electric mixer.
Beat on high until medium peaks form.
Dollop on top of pumpkin pie bar slices.
Sprinkle with cinnamon for garnish, if desired.