Mom's Tuna Noodle Casserole

"I remember this casserole from when I was a little girl.  It's definitely comfort food!"

1 box of macaroni and cheese, prepared (butter & milk called for on box)

1 can of cream of mushroom soup

1 celery stalk, chopped

1/2 onion, chopped

1 can of peas, drained

1 can of tuna, drained

1 sleeve of butter crackers (I use Ritz crackers), crushed

2 Tbsp. butter, melted

Mix together prepared macaroni and cheese, soup, celery, onion, peas and tuna.  Place in baking dish that has been sprayed with non-stick cooking spray.  Combine cracker crumbs and melted butter and sprinkle on top.  Bake at 350 degrees for 30-40 minutes.