Heat a medium skillet over medium heat and melt 2 tablespoons butter. Add onions, season with bay, thyme, salt and pepper. Cook onions slowly, adding a splash of water if they get dry or brown to quickly, and cook 30 minutes until very soft and sweet. Add stock, remove bay leaf and keep warm over low heat.
Combine meat with salt, pepper, Worcestershire, granulated garlic and onion, Parm and a fat drizzle of oil. Make 4 large, thin patties that are even thinner at the center than the edges for even cooking.