Preheat broiler with oven rack 7 inches from heat. Cook bacon in a skillet over medium heat until crisp; crumble. Reserve 1 Tbsp. drippings. Place red onion on a baking sheet; brush with drippings. Broil 4 minutes per side; reduce oven temperature to 400°. Whisk together cream, salt, pepper, and eggs. Unfold pastry; roll to a 12-inch square on a floured surface, and fit into a greased 9-inch tart or quiche pan. Sprinkle 1 cup Swiss cheese and half of crumbled bacon onto crust; top with green onions and red onions. Pour cream mixture over onions. Fold excess dough toward center. Sprinkle center with Parmesan and remaining bacon and Swiss cheese. Combine yolk and milk; brush over dough. Bake at 400° for 40 minutes or until golden. Let stand 10 minutes. Serve with Pea-and-Green Onion Soup.