How to Make It
Preheat oven to 350°F. Roll piecrust out on a lightly floured work surface to a 12-inch circle. Fit piecrust inside a 9-inch pie plate, pressing into bottom and up sides of plate. Fold crust edges under; crimp as desired. Place a piece of parchment paper over crust in pie plate, leaving a 3-inch overhang. Fill with pie weights or dried beans. Bake in preheated oven 15 minutes. Carefully remove parchment paper and pie weights. Bake an additional 5 minutes. Remove from oven. (Do not turn off oven.)
Beat pumpkin, egg yolks, sugar, milk, flour, cinnamon, vanilla, nutmeg, salt, and cloves with an electric mixer fitted with a whisk attachment on medium speed until smooth, about 1 minute.
Beat egg whites in a separate bowl with an electric mixer fitted with a whisk attachment on high speed until soft peaks form, about 2 minutes. Fold into pumpkin mixture. Pour into piecrust.
Bake at 350°F until center is set, about 55 minutes. Let cool completely on a wire rack, about 1 hour.