Place Puff Pastry (1 sheet) into a pie plate. Sprinkle Cheese (1/2 cup) over the bottom.
Fry up Yellow Onion (1) and Bacon (4 slice), then add them on top of the cheese. Crack Egg (6) over top.
Place the other Puff Pastry (1 sheet) over top and press edges to seal. Trim off excess pastry from the sides. Using a fork, press around the edge of the pie. Using a knife, poke a small hole in the middle.
Beat the Egg (1) to make an egg wash. Brush the top of the pie with egg wash.
Bake at 220 degrees C (425 degrees F) for 20-25 minutes, or until the pastry is golden brown.
Let cool for 15-20 minutes.