Continue to simmer, stirring constantly and mashing until thick and shiny, 10-15 minutes. Remove from heat and whisk in cream mixture until fully incorporated. Strain through a fine-mesh strainer set over a medium bowl, using back of spatula to press.  Or with a Vitamix blender, process until smooth. Rewhisk mixture and transfer to warm prebaked pie shell.

Return pie plate with baking sheet to oven and bake pie 10 minutes. Reduce oven to 300F and continue baking until edges of pie are set and  center looks firm but jiggles slightly (thermometer inserted in center 175 F), 20-35 minutes (or more). Transfer pie to wire rack and cool to room temperature, 2 to 3 hours. Serve with whipped cream. Leftovers should be stored in refrigerator up to 3 days.