In a skillet, heat a drizzle of oil over medium heat. Add the ground beef, breaking it apart with a spatula and cooking until browned, about 5–7 minutes. Stir in the chopped onion, cooking until softened and translucent, about another 3 minutes. Mix in the ketchup, mustard, salt, and pepper, then let it simmer for about 2–3 minutes to meld the flavors while you prepare the crust.

Preheat your oven to 375°F (190°C). Roll out your pie crust on a floured surface, then carefully transfer it into a pie dish, pressing it gently against the sides and bottom. Trim any excess dough and prick the bottom with a fork.

Spoon half of the seasoned meat mixture into the prepared pie crust, spreading it evenly. Generously sprinkle half of the shredded cheddar cheese over the meat. Repeat with the remaining meat and top with the rest of the cheese.

Gently place the Cheeseburger Pie into the preheated oven and bake for 25–30 minutes until the cheese is bubbly and golden.

Once baked, carefully remove the pie from the oven and allow it to rest for about 5 minutes. Cut into wedges and serve hot.