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 Spinach Casserole?

You need 10 ingredients. The key ingredients include: 2 (10 oz.) pkg. chopped spinach, drained, 1/4 c. butter or margarine, 1/4 c. flour, salt and pepper to taste, and more.

Is Tuna Spinach Casserole suitable as seafood?

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

How do I store leftover Tuna Spinach Casserole?

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

Tuna Spinach Casserole Recipe

Name: Tuna Spinach Casserole
Prep time: 15 min
Cook time: 30 min
Total time: 45 min
Yield: 4 servings
Ingredients: 2 (10 oz.) pkg. chopped spinach, drained; 1/4 c. butter or margarine; 1/4 c. flour; salt and pepper to taste; 1/4 tsp. dry mustard; 1/8 tsp. onion salt; 2 c. milk; 1/2 c. mayonnaise; 1 Tbsp. lemon juice; 2 (6 oz.) cans tuna, drained

Try this homemade Tuna Spinach Casserole recipe the whole family will love. Made with chopped spinach, butter, flour and salt. Easy step-by-step instruc…

This Tuna Spinach Casserole relies on simple, everyday ingredients such as butter or margarine, flour, salt and pepper to taste and dry mustard. It comes together quickly and makes 4 servings, at about 510 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.
A good 1:1 gluten-free flour blend works well if you need a gluten-free version.

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

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Tuna Spinach Casserole

Tips for the best results

Variations & substitutions

My Personal Notes

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