1 tbsp. butter
1/4 c. chopped onion
1/2 c. chopped celery
1 can (10 3/4 oz.) cream of mushroom soup
1/2 c. mayonnaise
1 can (6 1/2 oz.) tuna, rinsed, drained and flaked
2 c. cooked egg noodles
1/4 c. crushed potato chips

Place butter, onion and celery in 1 1/2 quart glass casserole. Microwave for about 3 minutes on high or until partially cooked. Stir in remaining ingredients except potato chips. Sprinkle with crushed potato chips.

Microwave for about 8 minutes on roast or until heated through (about 150 degrees). Let stand 5 minutes before serving. 4 to 6 servings.