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 c. water, 1 tsp. chicken bouillon granules, 1 (10 oz.) pkg. frozen green beans, 1 c. 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 c. water; 1 tsp. chicken bouillon granules; 1 (10 oz.) pkg. frozen green beans; 1 c. chopped onion; 1 c. sliced fresh mushrooms; 1/4 c. chopped celery; 1 garlic clove, minced; 1/2 tsp. dill weed; 1/2 tsp. salt; 1/8 tsp. pepper; 4 tsp. cornstarch; 1 1/2 c. milk; 1/2 c. shredded Swiss cheese; 1/4 c. mayonnaise; 2 1/2 c. medium noodles, cooked and drained; 1 (12 1/4 oz.) can tuna, drained and flaked; 1/3 c. dry bread crumbs; 1 Tbsp. butter or margarine

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

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 994 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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