The basic ingredients for a baked tuna noodle casserole include egg noodles, peas, cream of mushroom soup, milk and tuna. Some recipes call for bread crumbs or crushed crackers for a crunchy topping.
The egg noodles make up the bulk of a tuna noodle casserole. The noodles need to be cooked before stirring them into the casserole. A package of frozen peas can go into the noodle water for the last two minutes of cooking time so they start to thaw and cook without getting mushy.
The rest of the ingredients go into the casserole without being cooked first. If the tuna comes in a can, it needs to be drained before adding it to the mixture. Tuna in a foil pouch usually does not need to be drained, as it does not have much water or oil in it.
Peas are the traditional vegetable used in a tuna noodle casserole, but other vegetables can also go into the mixture. When using frozen vegetables, a quick boil with the noodles is recommended. Canned vegetables can go straight into the casserole after they are drained.
Other seasonings and additions add flavor to the casserole according to personal preference. Shredded cheese is one option. All seasonings and ingredients get stirred together before being poured into a greased casserole dish. If bread crumbs or crushed crackers are used, they go on top of the other casserole ingredients just before baking.