Roll 2 shells out onto a lightly floured surface to make a 6-inch circle. Place one Brie cheese round in the middle of the pastry. Top with the remaining pastry. Dampen the edges with water. Crimp and seal edges together. Set on an ungreased baking sheet. Repeat with the remaining patty shells and Brie cheese. Beat the egg yolk and water well with a fork. Brush the tops of the pastry and bake in a preheated oven at 375 F for about 20 minutes until golden. This makes 3 rounds and each round cuts into 8 wedges. Makes 24 wedges in total. Serve with assorted crackers and sliced apples and pears dipped in lemon juice to prevent rusting.
