Preheat oven to 350 degrees F. Grease a 1-quart casserole dish.
Cook the ramen noodles as directed, using or discarding the flavor packet as desired.
Add the drained tuna fish, the mixed vegetables, and the cheese. You may also add the mayonnaise if you wish your casserole to be creamier. Reserve some of the cheese to top the casserole, if desired, or use extra cheese.
Pour into a small casserole dish and bake in the preheated oven until bubbly or heat in the microwave.