2 lbs ground chuck  | 
                                                1/2 cup prepared horseradish  | 
                                                1/4 cup minced yellow onion  | 
                                                salt & freshly ground black pepper  | 
                                                16 slices havarti cheese or 8 ounces cheese, sliced into 8 slices  | 
                                                8 large hamburger buns, split  | 
                                                catsup, on the side for serving  | 
                                                mayonnaise, on the side for serving  | 
                                                mustard, on the side for serving  | 
                                                bacon, on the side for serving  | 
                                                lettuce, on the side for serving  | 
                                                tomato, on the side for serving  | 
                                                sliced onion, on the side for serving  |