1 can condensed cream of celery soup
1 c. milk
1 can water packed tuna, drained
1 c. uncooked elbow macaroni
1 c. frozen peas
1/2 c. chopped onion
1 c. shredded Cheddar cheese, reserve 1/4 c.

Whisk soup and milk in 2 quart microwavable bowl until well blended. Stir in remaining ingredients except reserved 1/4 cup cheese. Cover and refrigerate at least 12 hours or overnight. Cover with lid or vented plastic wrap. Microwave on high 15 to 17 minutes until bubbly. Sprinkle with reserved cheese. Let stand 5 to 7 minutes uncovered.