1. Preheat oven to 375 degree F and arrange racks in upper and lower thirds of oven. Unfold 1 piecrust on a lightly floured surface. Using a floured rolling pin, roll out into a 13-inch round, then cut out three 6-inch rounds. Fit into 3 pie tins and decoratively flute edges. Repeat with remaining piecrusts to make a total of 12 pie shells. Prick bottoms with a fork and freeze until firm, about 15 minutes.
2. Line shells with foil and fill with pie weights or dried beans; bake on 2 large baking sheets, switching pans halfway through, until bottoms are pale golden, about 15 minutes. Transfer tins to racks and cool shells to room temperature.
3. Lightly beat 1 egg in a small bowl. Brush edges of shells with egg. Whisk together pumpkin, half-and-half, remaining 5 eggs, sugar, cinnamon, salt, nutmeg, allspice, ginger, and cloves. Pour into shells, spreading evenly, and bake in middle of oven until filling is just set and center juggles slightly when gently shaken, 25 to 30 minutes. Transfer pies in pans to racks to cool. Serve at room temperature or chilled. Makes 12 servings.