Cook elbow macaroni per package directions; drain and rinse with cold water.
Put noodles into a large bowl. Add Miracle Whip, mayonnaise, and mustard to the mixture; mix well. Add salt & pepper; mix well. Coarsely chop celery and add to mixture. Flake in the tuna and add the frozen peas (don't thaw or cook them); mix all together.
Cube the blocks of cheese. Immediately before serving, add the cheese. Sprinkle some French fried onions over the top of the mixture if desired.