Preheat oven to 350 degrees F. Roll pie crust out on a lightly-floured work surface to a circle roughly 12 inches in diameter. Transfer to a plate, rolling up overhanging edge and refrigerate for 30 minutes. Whisk egg with cream. Transfer to a 9-inch pie plate, then, using kitchen shears or a paring knife, trim crust around edge of pie plate. Crimp crust edge, then brush crimped edge with egg wash and sprinkle with demerara sugar . Line bottom of crust with a round of wax paper, add dried beans or pie weights, and bake crust until edge is golden, about 15 minutes. Remove weights and wax paper and bake crust until bottom and side is golden, about 5 minutes longer. Let cool slightly.
