Parbake your crust in a 9" deep dish pie plate. Let cool for ten minutes.
Use a food processor to combine the pumpkin, brown sugar, and all four spices until smooth. Next add the eggs, one at a time, pulsing briefly after each addition. Add the cream and syrup and pulse just until smooth.
Pour filling into crust and bake 60-65 minutes or until puffed around the edge and firm in the center.
Let pie cool completely on a wire rack. Refrigerate for about an hour after cooled.
Beat heavy cream with powdered sugar until firm peaks form and spread on top of pie. Optionally, you can sprinkle with a little cinnamon sugar for garnish.
Keep refrigerated until ready to serve.
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