Cheeseburger Casserole
["2 Tbsp. butter", "6 slices white bread, toasted", "1 lb. lean ground beef", "1 small onion, cut up", "1/4 c. chopped celery", "1 Tbsp. yellow mustard (prepared)", "1 tsp. salt", "1 c. shredded Cheddar cheese", "1 egg", "3/4 c. milk", "1/8 tsp. dry mustard", "1/4 tsp. paprika"]
["Preheat the oven to 350\u00b0.", "Spread butter on both sides of the bread. Cut slices in half and set aside. Brown the ground beef. Add onion, celery, prepared mustard and 1/2 teaspoon of salt.", "In a buttered 9 x 9 x 2-inch baking dish, place alternate layers of toast, beef mixture and cheese.", "In a small bowl, beat the egg, then stir in the milk, dry mustard and the remaining salt.", "Pour mixture over the cheese. Sprinkle with paprika and bake, uncovered, for 25 minutes."]
["butter", "white bread", "lean ground beef", "onion", "celery", "yellow mustard", "salt", "Cheddar cheese", "egg", "milk", "dry mustard", "paprika"]