A family favorite casserole and a flavorful way to use leftover mashed potatoes.
Melt butter in large nonstick skillet on medium-high heat. Add onion, carrots and mushrooms; cook and stir 5 minutes or until vegetables are tender. Add ground beef; cook and stir 5 minutes or until meat is no longer pink. Stir in marinade and tomato paste until well blended. Add peas; stir gently.
Spoon mixture into 2-quart casserole. Spread evenly with potatoes.
Broil 5 to 6 minutes or until golden brown.
Substitution Tip: Use 2 1/2 cups leftover mashed potatoes, heated, in place of the prepared mashed potatoes.