1. Preheat oven to 350 degrees F.
  2. Boil water and cook elbow macaroni to desired softness.
  3. While your pasta is cooking, combine the tuna, olives and cream of mushroom soup into a large bowl. Be sure to scrape the tuna out of the can with a fork, to ensure the tuna is not in large chunks, but flaked into small pieces. **If you are making your casseroles half-and-half, combine 1 can of olives, 1 can of tuna and 1 can of cream of mushroom into a medium bowl. Combine the second can of tuna, the second can of cream of mushroom and 1 cup of frozen peas into a separate medium-sized bowl.
  4. Add your cooked pasta to the large bowl, and evenly cover your noodles with your cream of mushroom mixture. **If you are making your casseroles half-and-half, add one of your noodles to each medium sized bowl, evenly covering with your cream of mushroom mixture.
  5. Spread noodle mixture evenly into a casserole dish. **If you are making your casseroles half-and-half, you can use one casserole dish with the pea mixture on one side and the olive mixture on the other, or you can add separately to two smaller casserole dishes.
  6. Sprinkle the top of your casserole(s) with breadcrumbs, you want a light coating that will add just a bit of crunch.
  7. Bake casserole for 25 minutes, or until heated through. This really doesn’t take long, because the noodles have already started to heat the casserole through, and nothing in the casserole needs to be cooked. **If you are making your casseroles in 2 dishes, reduce cook time by 5-10 minutes, cooking both casseroles at the same time.