In a large bowl combine ground beef, onion, garlic, mustard, Guinness, olive oil, salt, and pepper. Mix using your hands until just combined. Be careful not to overmix.
Preheat the grill or griddle to medium-high heat. Lightly grease the grill grates. Add to the grill and cook, turning at least once, until fully cooked (the internal temperature has reached 160 degrees F.). During the last minute of cooking top each patty with a slice of cheddar cheese, cook until the cheese has melted.
Place burgers onto English muffins and top with bacon.