Cook the bacon in a large skillet over medium heat, stirring occasionally, until crisp, about 4 minutes. Transfer to a paper towel-lined plate using a slotted spoon; discard all but 1 tablespoon of the drippings from the skillet.

Reduce the heat to low and add the butter to the skillet; swirl to melt. Add the onions; cover and cook, stirring occasionally, until golden, about 15 minutes. Uncover and add the garlic. Cook, stirring occasionally, until the onions are lightly caramelized, about 5 minutes. Add the vinegar and cook, stirring, until the onions are glazed, about 1 more minute. Stir in the reserved bacon and season with salt and pepper; set aside.

Form your patties, just lightly salting and peppering the meat. Grill to your desired heat.. I am a medium rare guy and my wife is a rare girl. Toast your buns while meat is grilling. Top with the Gruyere for the last minute or so to allow to melt.

Serve on toasted bun with the Onion Bacon compote and top with crumbled Blue cheese and watercress.