Heat a large sauté pan over medium high heat. Add chopped bacon until crisp; remove to a paper towel-lined plate and pour off some of the bacon fat. To the same sauté pan, add ground beef, breaking it up into small pieces. After the meat is browned, add the bacon back into the meat and stir in ketchup and mustard.
Heat a non-stick griddle over medium heat. Meanwhile, build your quesadillas, starting with a tortilla, a layer of shredded cheddar, a layer of the ground beef and bacon, another layer of cheese, then top with a second flour tortilla. Place on griddle for 5-10 minutes or until the tortilla is golden brown and the cheese is melted.
Serve garnished with some lettuce, tomatoes and pickles.