These pastries make a stunning first course when filled with a seafood stew, soft scrambled eggs, or creamed mushrooms. For best results, use a vol-au-vent cutter, although round cookie cutters can also be used.
Lightly flour a clean work surface. Using a rolling pin, gently roll out dough until it is about 1/4 inch thick. Using a 4-inch vol-au-vent cutter, cut out 4 rounds. If using a 3 1/2-inch cookie cutter, cut out 8 rounds; cut out centers from half the rounds with a 2 1/2-inch round cookie cutter to form rings.
In a small bowl, whisk together egg yolk and cream. Using a pastry brush, moisten top of each vol-au-vent with egg wash, being careful not to let any drip down over the cut edges. (Or moisten each ring and round with egg wash; lay one ring on top of each round, lining up outside edges.) Place vol-au-vents on an ungreased baking sheet. Cover with plastic wrap; place in refrigerator 1 hour.
Preheat oven to 425 degrees. Bake until vol-au-vents are puffed and golden on the outside, about 12 minutes. Reduce heat to 350 degrees; continue baking 10 to 12 minutes to let insides cook through.
Transfer vol-au-vents to a wire rack. While still warm, cut out center of tops with a paring knife; set aside. Remove and discard inside dough, and let shells cool completely. Spoon or pipe in desired filling. Replace tops, and serve.