1. Cook the Cheeseburger Filling

Heat a large skillet over medium heat and add the ground beef. Cook for 2-3 minutes, breaking it up with a spatula as it browns. Add the diced onion and continue cooking until the beef is fully cooked and the onions are softened, about 5-6 minutes. Drain any excess grease from the skillet.

Reduce the heat to low and stir in the ketchup, mustard, Worcestershire sauce, garlic powder, onion powder, smoked paprika, salt, and pepper. Mix well until the beef is coated in the flavorful sauce. Taste and adjust seasoning if needed. Remove the beef mixture from heat and let it cool slightly.

2. Assemble the Quesadillas

Lay one tortilla flat on a clean surface or cutting board. Sprinkle 1/4 cup of shredded cheddar cheese evenly over half of the tortilla. Add a generous layer of the cheeseburger filling (about 1/4 of the mixture), then top with additional cheese (1/4 cup of Monterey Jack).

If desired, sprinkle on optional add-ins like chopped pickles, crumbled bacon, or diced tomatoes. Fold the tortilla in half to create a half-moon shape, pressing gently to secure the filling. Repeat this process with the remaining tortillas and filling.

3. Cook the Quesadillas

Heat a large nonstick skillet or griddle over medium heat and add 1/2 tablespoon of butter (or a drizzle of oil). Once melted, place one quesadilla in the skillet and cook for 2-3 minutes on each side, or until the tortilla is golden brown and crispy, and the cheese is melted. Use a spatula to carefully flip the quesadilla.

Transfer the cooked quesadilla to a cutting board and let it rest for 1 minute before slicing into wedges. Repeat with the remaining quesadillas, adding more butter or oil to the skillet as needed.

4. Serve and Enjoy

Arrange the quesadilla slices on a serving platter and garnish with additional toppings if desired. Serve warm with dipping sauces like ketchup, mustard, ranch, or homemade burger sauce.