Preheat oven to 350 degrees F. Heat 2 tablespoons clarified butter in large overproof pan. Pat meat dry and add a little at a time to brown.
In a separate pan, heat remaining clarified butter. Add onions and lightly brown. Add 2 tablespoons fresh butter, then stir in flour. Cook until lightly browned.
Add onions to meat and combine well. Add beef stock and stir until sauce thickens. Season with salt and pepper. Add Worcestershire sauce, sugar, and bay leaves. Spoon off 1/2 cup of the gravy and reserve. Lay kidney slices on top, followed by mushrooms, then oysters. Season with salt and pepper. Cover with overlapping potato slices. Season again and add back 1/2 cup reserved gravy. Roast in oven for 1 hour, uncovered.
Remove stew from oven and turn up to broil. Broil hot pot for 2 1/2 minutes to brown. Garnish with parsley.