Preheat oven to 350 degrees F (175 degrees C). In a 5 quart saucepan combine both soups and add milk. Once it is heated add cubed Velveeta cheese. Stir until consistency is smooth. Once it is smooth, combine the macaroni, sweet peas, Old Bay seasoning and tuna. Mix well. Pour mixture into a 9x13-inch baking dish and then top with shredded cheese.
Bake at 350 degrees F (175 degrees C) for about 25 minutes, or until bubbly. Sprinkle with fried onions, and bake for another 5 minutes. Serve hot.