Brown the ground beef in a skillet over medium-high heat, breaking it apart. Season with salt and pepper. Set aside.
Crisp the bacon in a separate pan. Drain on paper towels, then crumble.
Whisk mayo, ketchup, and mustard in a bowl until smooth.
Heat tortillas in a dry skillet for 20–30 seconds per side until soft.
Layer beef, bacon, cheddar, mozzarella, sautéed onion, lettuce, and tomato down the center.
Drizzle with cheese sauce and burger sauce.
Fold in sides, roll tightly from the bottom to seal.
Slice if desired. Serve warm with extra sauce or toppings.