Step 1Heat the oven to 350 degrees. Lightly grease a 13x9-inch casserole or two smaller ones.
Step 2Prepare the noodles according to the package directions and drain. Set aside.
Step 3Cook the celery and onions in the margarine in a small skillet over medium heat until soft, 8 to 10 minutes.
Step 4In a large bowl, combine the noodles, celery and onion mixture, tuna, peas, milk, sour cream, soup, cheese, salt and pepper to taste, parsley, dill and Old Bay Seasoning. Toss well.
Step 5Spoon the noodle mixture into the casserole. Sprinkle the crumbled crackers evenly over the top, then drizzle with 2 tablespoons melted margarine (this assists browning). Sprinkle lightly with the paprika.
Step 6Bake the casserole until the top is golden brown and it is evenly hot throughout, 30 minutes.