Preheat oven to 375 °F (190 °C). Place a pie dish on a baking sheet.
Cook chopped bacon in a skillet over medium heat until crispy. Remove and set aside, keeping some bacon fat in the pan.
Add ground beef and chopped onion to skillet. Cook until beef is browned and onions are soft, breaking up the meat.
Stir in minced garlic, Worcestershire sauce, mustard, salt, and pepper. Drain excess fat.
Return cooked bacon to the beef mixture and mix well. Remove from heat and let cool slightly.
Stir in half of the shredded cheese.
Place the pie crust in the pie dish and gently press to fit.
Spoon the beef and bacon filling evenly into the crust. Sprinkle remaining cheese on top.
If desired, brush crust edges with beaten egg.
Bake for 25–30 minutes until crust is golden and cheese is melted and bubbly.
Let pie rest a few minutes before slicing. Serve topped with pickles, tomatoes, lettuce, ketchup, and mustard if desired.