How many servings does this recipe make?

This recipe makes 4 servings. You can adjust the portion size directly on this page.

What ingredients do I need for Tuna Mushroom Casserole?

You need 18 ingredients. The key ingredients include: 1/2 cup water, 1 teaspoon chicken bouillon granules, 1 package (9 ounces) frozen cut green beans, 1 cup chopped onion, and more.

Is Tuna Mushroom Casserole suitable as seafood?

Yes, Tuna Mushroom Casserole falls under the Seafood category and is a great choice for this type of meal.

How do I store leftover Tuna Mushroom Casserole?

Store leftovers in an airtight container in the refrigerator for up to 3–4 days. Reheat gently before serving.

Tuna Mushroom Casserole Recipe

Name: Tuna Mushroom Casserole
Prep time: 15 min
Cook time: 30 min
Total time: 45 min
Yield: 4 servings
Ingredients: 1/2 cup water; 1 teaspoon chicken bouillon granules; 1 package (9 ounces) frozen cut green beans; 1 cup chopped onion; 1 cup sliced fresh mushrooms; 1/4 cup chopped celery; 1 garlic clove, minced; 1/2 teaspoon dill weed; 1/2 teaspoon salt; 1/8 teaspoon pepper; 4 teaspoons cornstarch; 1-1/2 cups cold whole milk; 1/2 cup shredded Swiss cheese; 1/4 cup mayonnaise; 2-1/2 cups egg noodles, cooked and drained; 1 can (12 ounces) light tuna in water, drained and flaked; 1/3 cup dry bread crumbs; 1 tablespoon butter

Try this homemade Tuna Mushroom Casserole recipe the whole family will love. Made with water, chicken bouillon granules, green beans and onion. Easy ste…

This Tuna Mushroom Casserole relies on simple, everyday ingredients such as water, chicken bouillon granules, chopped onion and sliced fresh mushrooms. It comes together quickly and makes 4 servings, at about 614 kcal each. The step-by-step instructions below are written to be easy to follow, even on a busy day.

It's versatile enough for an easy weeknight dinner yet satisfying enough for guests at the weekend. Serve it with your favorite sides, and keep any leftovers for a quick meal the next day.

Updated Jun 30, 2026

Serves 4 Seafood

Tips for the best results

Read through all the steps once before you start and measure out your ingredients first — it makes everything go more smoothly.
Taste as you go and adjust the seasoning before serving.
Avoid overcrowding the pan — cook in batches if needed for the best texture.
Let the dish rest for a few minutes before serving so the flavors settle.
Store leftovers in an airtight container in the fridge and enjoy within a few days.

Variations & substitutions

Use a neutral oil or a plant-based spread in place of butter for a dairy-free version.

No specific allergen information. Please check the ingredient list for possible allergens.

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Tuna Mushroom Casserole

Tips for the best results

Variations & substitutions

My Personal Notes

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