Tuna and Potato Bake: An Easy Family Meal

This easy tuna potato bake costs $13.53 total, or about $2.26 per serving, and feeds six people. It comes together in about 75 minutes from start to finish.

Tender potatoes, creamy tuna, and vegetables bake under a golden cheese crust, so it is a complete meal in one pan with easy cleanup.

What this costs

These are estimated costs based on typical U.S. supermarket store-brand prices in September 2026. Prices vary by store and region, so treat them as a guide.

Ingredient cost = pack price ÷ pack quantity × amount used. Cost per serving = total recipe cost ÷ servings.

Ingredient Notes and Cheaper Swaps

Leek

Leeks add a subtle, sweet onion flavor to the sauce. If you can’t find them or want a cheaper option, use a medium yellow onion, finely diced and sautéed until very soft, or a couple of extra green onions.

Canned Tuna

Canned tuna in water is usually the most economical choice, and store brands often offer the best value. If you use tuna in oil, drain it well to prevent an oily casserole. Canned salmon or shredded cooked chicken can replace the tuna, though they might slightly increase the cost. For a different way to use your canned tuna, make tuna croquettes and serve them with a salad.

Cheese Blend

The recipe calls for a pre-grated pizza cheese blend, which often contains mozzarella and provolone. Buying a block of cheese and grating it yourself is often cheaper and melts more smoothly. Sharp cheddar, Monterey Jack, or whatever melty cheese is on sale also works.

Potatoes

Russet or Yukon Gold potatoes become tender and creamy when baked. Slice them thinly and uniformly so they cook evenly; you can leave the skin on if they are well scrubbed. Leftover cooked potatoes can be sliced and layered, reducing the baking time slightly. If your leftovers are already mashed, use them for air fryer potato pancakes instead.

How to Make Tuna Potato Bake Step by Step

Preheat the oven and lightly grease a baking dish. Melt the butter in a saucepan over medium heat, add the thinly sliced leek, and cook gently until softened and fragrant but not browned. Stir in the flour and cook for a minute, letting it bubble to form a roux.

Add the milk a little at a time, whisking constantly to keep the sauce smooth. Stir until the sauce comes to a boil and thickens, which can take a few minutes, then stir in the Dijon mustard.

Fold in the drained, flaked tuna, frozen peas, corn, and baby spinach and cook for a couple of minutes, until the spinach wilts and everything is warmed through. Stir in the green onions and about two-thirds of the shredded cheese, then transfer the mixture to the prepared baking dish.

Arrange the thinly sliced potatoes over the tuna mixture, overlapping them slightly, and sprinkle the remaining cheese over the top. Bake until the potatoes are fork-tender and the cheese is bubbly and golden brown. Let it rest for a few minutes so the sauce sets. For full quantities and detailed steps, refer to the recipe card below.

Tips for the Best Results

• Slice Potatoes Evenly: Use a sharp knife or a mandoline to slice the potatoes thin and consistent so they cook through at the same rate.
• Don’t Overcook Tuna Mixture: On the stove, cook it only until warmed through and the spinach wilts; it continues to cook in the oven.
• Golden Crust: If the cheese isn’t browning by the end of the baking time, place the dish under the broiler for 1-2 minutes, watching closely to prevent burning.
• Rest Before Serving: Letting the casserole stand for 10 minutes after baking helps the sauce set, making it easier to serve clean portions.

Storing, Freezing and Reheating

Cool leftovers completely, then refrigerate them in an airtight container for 3-4 days. Reheat individual portions in the microwave, or the entire dish in an oven preheated to 350°F (175°C) for about 20-30 minutes, until heated through. If it seems dry, add a splash of milk before reheating.

To freeze, transfer cooled portions to freezer-safe containers for up to 2-3 months, and thaw overnight in the refrigerator before reheating. The potatoes can become a little mealy after freezing and thawing.

Serving Ideas and Variations

• Simple Side Salad: A crisp green salad with a light vinaigrette balances the rich casserole.
• Add a Kick: Stir a pinch of cayenne pepper or a dash of hot sauce into the tuna mixture.
• Extra Veggies: Add diced bell peppers, chopped celery, or canned artichoke hearts (drained well) to the tuna mixture.
• Different Topping: Sprinkle breadcrumbs mixed with a little melted butter over the cheese for a crispy, golden topping.

To keep potatoes on the menu with a change from casserole, make a batch of potato soup you can freeze.

Emily Carter

Tuna Potato Bake

A comforting and budget-friendly tuna potato bake featuring creamy tuna and vegetables topped with tender potato slices and melted cheese.

Print Recipe Pin Recipe

Prep Time 20 minutes mins

Cook Time 55 minutes mins

Total Time 1 hour hr 15 minutes mins

Servings: 6 servings

Course: Main Course

Cuisine: American

Calories: 651

Ingredients Equipment Method Notes

Ingredients

  

• 5 tablespoons unsalted butter chopped
• 1 leek trimmed, thinly sliced
• ½ cup all-purpose flour
• 4 cups milk
• 1 ½ tablespoons Dijon mustard
• 2 cans tuna in water 15 oz each, drained and flaked
• ½ cup frozen peas
• ½ cup frozen corn
• 2 oz baby spinach
• 3 green onions thinly sliced
• 1 ½ cups shredded cheese blend (such as mozzarella and cheddar)
• 3 large potatoes washed, unpeeled, thinly sliced
• ½ teaspoon salt
• ¼ teaspoon black pepper
• cooking spray or oil for greasing

Equipment

• 1 9×13 inch baking dish
• 1 large saucepan
• 1 whisk
• 1 Sharp knife
• 1 Cutting board

Method

 

1. Preheat your oven to 425°F. Lightly grease a 9×13 inch baking dish.
2. Melt butter in a large saucepan over medium heat until foaming. Add the sliced leek and cook, stirring occasionally, for 3 minutes until softened.
3. Stir in the all-purpose flour and cook, stirring with a wooden spoon, for 1 minute until the mixture bubbles and forms a roux.
4. Gradually add the milk, about 1/2 cup at a time, whisking constantly to prevent lumps. Continue to stir until all the milk is incorporated and the sauce boils and thickens, about 3 minutes.
5. Stir in the Dijon mustard until well combined. Add the drained and flaked tuna, frozen peas, frozen corn, and baby spinach. Cook, stirring, for 2 minutes or until warmed through and the spinach wilts.
6. Remove from heat. Stir in the green onions and 1 cup of the shredded cheese blend. Continue to stir for 1 minute until the cheese melts into the sauce.
7. Transfer the tuna mixture to the prepared baking dish and spread evenly.
8. Arrange the thinly sliced potatoes over the tuna mixture, slightly overlapping them to create an even layer.
9. Sprinkle the remaining 1/2 cup of shredded cheese over the potatoes.
10. Bake for 45 minutes or until the potatoes are golden and tender, and the cheese is bubbly and lightly browned. If desired, broil for the last 1-2 minutes for extra crispness.
11. Remove from the oven and let stand for 10 minutes before serving to allow the casserole to set.

Notes

For an even quicker prep, you can use pre-sliced potatoes if available, though they are often more expensive. Ensure your potatoes are sliced uniformly thin for even cooking.

If you don’t have leeks, a finely diced yellow onion can be used as a budget-friendly alternative. Cook it until very soft before adding the flour.

Frequently Asked Questions

Share this recipe