The basics are covered here: https://www.spendwithpennies.com/easy-tuna-casserole/

But specifically and loosely:

1. Stir fry diced onion and frozen veggie mix (carrots, green beans, peas, corn) until onions are translucent.
2. Cook egg noodles.
3. In a bowl mix the onion, frozen veggies, can of cream of mushroom soup, 2 cans of light tuna, milk, 2 cups cheese, tablespoon of parsley, some chicken bouillon, a little sugar.
4. Transfer to casserole dish.
5. Top with more cheese, parsley. Brush with oil.
6. Bake for 20 minutes at 425F.