In a large skillet over medium heat on the stove, fry the bacon until crisp, 10 to 12 minutes, turning occasionally. Transfer the bacon onto paper towels to drain.
Gently form the ground chuck into six patties of equal size, each about 2 centimetres thick. Season both sides with salt and pepper. With your thumb or the back of a spoon, make a shallow indentation about 2.5 centimetres wide in the centre of the patties to keep them from forming a dome as they cook. Refrigerate until ready to grill.
Prepare the grill for direct cooking over medium–high heat (200°C to 260°C).
Brush the cooking grates clean. Grill the patties over direct medium–high heat, with the lid closed, until cooked to medium doneness (70ºC), 8 to 10 minutes, turning once. During the last minute of grilling time, top each patty with a slice of cheese to melt and toast the buns over direct heat.
Build each cheeseburger on a bun with a lettuce leaf, a slice of tomato, a patty and a slice of bacon. Serve with ketchup and mustard, if desired.