Prepare the Cheeseburger Filling

1. Cook the Ground Beef: In a large skillet, heat a bit of oil over medium-high heat. Add the ground beef, breaking it up with a spatula as it cooks. Stir occasionally, cooking until browned and cooked through, about 5-7 minutes.
2. Add the Aromatics: Add the chopped onion and garlic to the pan with the beef. Cook for 2-3 minutes, until softened and fragrant.
3. Season the Beef: Stir in the ketchup, mustard, Worcestershire sauce, and season with salt and pepper to taste. Let the mixture simmer for another 2 minutes, so the flavors meld together.

Assemble the Quesadillas

1. Heat the Tortillas: In a separate skillet, heat the tortillas one at a time over medium heat. Warm each tortilla for about 30 seconds per side, just enough to make it pliable for filling.
2. Fill the Tortillas: On one half of each tortilla, spoon a generous amount of the cheeseburger filling. Sprinkle with shredded cheddar cheese and any additional toppings you like, such as lettuce or pickles.
3. Fold the Tortilla: Fold the tortilla in half over the filling to form a half-moon shape.

Cook the Quesadillas

1. Fry the Quesadillas: In the same skillet, melt 1 tbsp of butter over medium heat. Once the butter is melted and sizzling, place the filled tortilla in the skillet. Cook for about 3-4 minutes per side, pressing down gently with a spatula, until the outside is golden brown and crispy, and the cheese has melted.
2. Repeat: Repeat the process with the remaining quesadillas, adding more butter to the pan as needed.

Serve and Enjoy

1. Slice and Serve: Once the quesadillas are golden and crispy, remove them from the skillet. Let them cool for a minute before slicing them into wedges.
2. Garnish: Optionally, serve with a side of sour cream, salsa, or your favorite dipping sauce. You can also top with additional lettuce, tomatoes, or pickles for extra flavor.