Combine ground chuck, parsley, basil, oregano, onion powder, salt and pepper; mix well. Portion into four patties and grill to 160 degrees internal temperature.
Top each burger with 3 tablespoons spaghetti sauce and 1 slice mozzarella. Close lid on grill to melt cheese slightly.
Brush focaccia bread with melted butter and toast on grill. Serve burgers on the grilled bread.