In a medium bowl, cut cream cheese and butter into flour with a pastry blender or two knives until particles resemble small peas. Shape into a ball. Wrap in foil or plastic wrap; refrigerate at least 1 hour. Divide dough into 2 pieces. On a lightly floured surface, roll out each piece about 1/8 inch thick. Cut each into a 6-inch circle, reserving excess dough for trim. Place 1 circle of dough on an ungreased baking sheet. Place whole Brie cheese in center of dough;top with other pastry circle. Pinch pastry edges together to seal. Preheat oven to 400. Roll out excess dough. Cut 1 decorative design with a cookie cutter and about 10 small designs with hors d'oeuvre cutters. Place large cut out on top of croute and small cut outs around side. Sprinkle with sesame seeds. Bake 15 to 17 minutes in preheated oven until golden brown. Let stand several minutes before cutting into. Serve warm. Makes 16-18 appetizer servings.