Overnight Tuna Casserole

Description
Purchased from Vega Estate in Longview, Texas in 1990. Dated 1952.
 * Contributed by Cat's Recipes Y-Group

Ingredients

 * 1 can cream of celery soup
 * 1 cup milk
 * 1 can water packed tuna, drained and flaked
 * 1 cup uncooked elbow macaroni
 * 3 tablespoons mustard
 * 1 tablespoon sour cream
 * 1 cup fresh peas
 * ½ cup chopped yellow onion
 * 1 cup grated Swiss cheese

Directions

 * 1) Whisk soup and milk in sauce pan until blended.
 * 2) Add remaining ingredients except ¼ cup cheese.
 * 3) Cover and refrigerate overnight.
 * 4) Bake in 350°F oven for 30 minutes.
 * 5) Sprinkle remaining cheese on top and place back in oven for 1-2 minutes while cheese melts.