This Tuna & Mashed Potato Casserole is a comforting, budget-friendly dish that transforms simple pantry staples—canned tuna, potatoes, tomato paste, and onions—into a heart-warming family meal. Layered much like a shepherd’s pie, it combines creamy mashed potatoes with a savory tuna–tomato filling, then crowns the assembly with gooey mozzarella cheese. Whether you’re feeding a crowd or simply craving a satisfying one-dish dinner, this casserole offers robust flavor, minimal fuss, and maximum satisfaction.
Cooking Time
Preparation Time: 15 minutes
Cooking Time (stove & assembly): 12 minutes
Baking Time: 10–15 minutes
Total Time: 37–42 minutes
Ingredients
-
5 medium potatoes (about 750 g), peeled and quartered
-
1 tsp salt (for boiling potatoes)
-
20 g (0.7 oz) unsalted butter
-
180 ml (6 fl oz) hot milk
-
Salt & freshly ground black pepper, to taste
-
2 tbsp extra-virgin olive oil
-
1 large onion, sliced into half-rings
-
2 cans (each ~150 g drained) tuna in brine or oil, drained
-
2 tbsp tomato paste
-
1 ladleful (about 100 ml) reserved potato-boiling water or broth
-
60 g (2 oz) mozzarella cheese, grated
Step-by-Step Cooking Directions
-
Boil the Potatoes
Place the peeled, quartered potatoes in a large pot. Cover with cold water, add 1 tsp salt, and bring to a boil. Reduce heat to a gentle simmer and cook 15–20 minutes, until a fork easily pierces each chunk. -
Sauté the Onion
While the potatoes cook, heat 2 tbsp olive oil in a large skillet over medium heat. Add the sliced onion and sauté 4–5 minutes, stirring occasionally, until soft and translucent. -
Add Tuna & Tomato
Drain the tuna cans, reserving about 100 ml of the liquid. Add the drained tuna to the onions, breaking up any large flakes with a wooden spoon. Stir in 2 tbsp tomato paste, then pour in the reserved potato water or broth. Mix thoroughly and simmer for 2–3 minutes over low heat. Season with salt and pepper to taste. -
Mash the Potatoes
Drain the cooked potatoes, return them to the empty pot, and add 20 g butter. Mash roughly, then pour in 180 ml hot milk gradually, mashing until you reach a creamy consistency. Adjust salt and pepper. -
Assemble the Casserole
Preheat your oven to 190 °C (375 °F). In a lightly greased baking dish, spread half of the mashed potatoes in an even layer. Spoon the tuna–onion mixture over the potatoes, then top with the remaining mashed potatoes, smoothing the surface. -
Add Cheese & Bake
Sprinkle 60 g grated mozzarella evenly over the top. Bake for 10–15 minutes, until the cheese melts and forms golden brown spots. -
Rest & Serve
Remove from oven and let rest 5 minutes. Scoop and serve warm, ensuring each portion has both mash and tuna filling.
Nutritional Information
(Per serving, 4 servings total)
-
Calories: 380 kcal
-
Protein: 23 g
-
Carbohydrates: 32 g
-
Fat: 17 g
-
Fiber: 3 g
-
Sodium: 520 mg
The Origins and Popularity of the Recipe
The Tuna & Mashed Potato Casserole marries European fish-pie traditions (notably Britain’s classic “tuna fish pie”) with North American shepherd’s pie techniques. Canned tuna became popular during the 20th century, offering an affordable protein. Combined with pantry staples like potatoes and tomato paste, these casseroles surged in popularity for their economy and ease—ideal for post-war households and busy midcentury families. Today, they remain a beloved comfort food, celebrated for minimal prep and reliable crowd-pleasing flavor.
Reasons Why You’ll Love the Recipe
-
Economical: Uses budget-friendly ingredients you likely already have on hand.
-
Comforting: Creamy potatoes and savory tuna create a warm, nostalgic flavor.
-
One-Dish Ease: Stove-to-oven simplicity means minimal cleanup.
-
Kid-Approved: Mild flavors and cheesy topping appeal to young palates.
-
Customizable: Add vegetables or herbs to suit your taste.
Health Benefits
-
Tuna: A lean source of omega-3 fatty acids and high-quality protein for heart and muscle health.
-
Potatoes: Provide potassium and fiber for blood-pressure regulation and digestive wellness.
-
Onions & Tomato Paste: Offer antioxidants (quercetin, lycopene) that support immune and cellular health.
-
Olive Oil: Rich in monounsaturated fats that aid cardiovascular health.
Serving Suggestions
-
Green Salad: A crisp side of mixed greens with lemon vinaigrette adds brightness.
-
Steamed Vegetables: Broccoli or green beans complement the richness of the casserole.
-
Bread: Warm crusty bread or rolls soak up extra sauce.
-
Condiments: A dollop of sour cream or plain yogurt adds tang.
Common Mistakes to Avoid
-
Underseasoning the Mash: Potatoes need ample salt and butter—taste as you go.
-
Overcooking Tuna: Heat only long enough to meld flavors; overcooking can dry out fish.
-
Skipping Reserved Liquid: The reserved potato-water or broth adds moisture and flavor to the tuna layer.
-
Dense Potato Layer: Don’t pack the mash too firmly; leave it light and fluffy for textural contrast.
Pairing Recommendations
-
Wine: A crisp Sauvignon Blanc balances the creamy mash and tuna’s richness.
-
Beer: A light pilsner or wheat beer refreshes the palate.
-
Non-Alcoholic: Sparkling water with a lemon slice cleanses between bites.
Cooking Tips
-
Even Slicing: Cut potatoes into uniform pieces for even boiling.
-
Flavor Boost: Stir in chopped parsley or chives into the mash for herbaceous notes.
-
Vegetable Add-Ins: Fold peas, corn, or diced carrots into the tuna mixture for extra color and nutrition.
-
Make-Ahead: Prepare the mash and tuna layer up to a day ahead; assemble and bake when ready.
Similar Recipes to Try
-
Shepherd’s Pie: Ground lamb or beef with veggies under mashed potato.
-
Fish Pie: Mixed seafood in a creamy white sauce topped with mash.
-
Tuna Noodle Casserole: Pasta, tuna, peas, and creamy sauce baked with breadcrumbs.
Variations to Try
-
Cheesy Herb Mash: Mix grated Parmesan and rosemary into the potatoes.
-
Spicy Twist: Add chili flakes or chopped jalapeño to the tomato paste layer.
-
Mediterranean Style: Stir in olives, capers, and feta into the tuna filling.
-
Gluten-Free: Use potato flour to bind tuna mix and ensure all ingredients are GF-certified.
Ingredient Spotlight
Canned Tuna
Canned tuna is a shelf-stable, cost-effective protein rich in omega-3 fatty acids, vitamin D, and selenium. Its mild flavor and flaky texture make it ideal for casseroles, salads, and sandwiches. Always choose sustainably caught varieties for environmental responsibility.
Conclusion
This Tuna & Mashed Potato Casserole is a trustworthy weeknight staple—simple to make, satisfying to eat, and budget-friendly. With its creamy potato layers, savory tuna filling, and golden cheese topping, it delivers comfort and flavor in every forkful. Customize it with your favorite add-ins, serve it alongside fresh greens, and watch it become a regular on your dinner rotation.
FAQ
-
Can I use tuna in oil instead of brine?
Yes—drain thoroughly and reduce added oil in the pan to prevent greasiness. -
How do I keep the mash light and fluffy?
Drain potatoes well, avoid over-mashing, and add milk gradually. -
Can I add frozen vegetables?
Absolutely—peas or mixed veggies folded into the tuna layer work beautifully. -
Is this casserole freezable?
Yes—assemble unbaked, freeze in airtight containers for up to 2 months. Bake from frozen, adding 10 minutes to cooking time. -
What can I substitute for mozzarella?
Cheddar, Gruyère, or a blend of cheeses can replace mozzarella. -
Can I make this gluten-free?
Omit tomato paste if it contains gluten and ensure any broth used is GF. The potato layer itself is naturally gluten-free. -
How do I reheat leftovers?
Reheat in a 180 °C oven for 10–12 minutes or microwave until warmed through. -
What’s the best way to serve it?
Allow a 5 minute rest after baking; serve with a crisp side salad. -
Can I add fresh herbs?
Yes—stir chopped parsley, chives, or dill into the mash for extra freshness. -
How can I reduce calories?
Use low-fat milk and butter, omit cheese topping, and increase vegetable content.