Chicken Asparagus Melt
["5 boneless skinless chicken breast halves", "2 Tbsp. oil", "2 small tomatoes (thinly sliced)", "1 lb. asparagus (cooked and drained) or 1 can Green Giant asparagu", "3 oz. (3/4 c.) shredded Mozzarella cheese", "Salt and Pepper to taste", "5 tsp. Dijon mustard"]
["Place each chicken breast half between 2 pieces of plastic wrap.", "Lightly pound chicken with flat side of meat mallet or rolling pin until 1/4-inch thick."]
["chicken", "oil", "tomatoes", "Mozzarella cheese", "Salt", "mustard"]