Prepare instant whipped potato flakes with water, 1/2 teaspoon salt, the milk and 1 tablespoon butter according to directions on package. Mix in onion. Spoon mixture equally into four individual baking dishes. Sauté meat until brown, in remaining 2 tablespoons butter; drain. Combine meat and remaining ingredients. Spoon equally into each potato-lined dish. Bake at 350° for 20 minutes. Garnish with onion rings and parsley, if desired.