Creamy Fish on Potato Gratin

Creamy Fish on Potato Gratin is a cozy, one-pan dish that delivers serious comfort with minimal effort. Flaky white fish is baked atop a bed of rich, garlicky potato gratin layered with tender leeks and topped with a golden, crispy parmesan-panko crust. It’s the kind of meal that feels luxurious, but is surprisingly simple to prepare—ideal for a relaxed weeknight dinner or a comforting dish to share with guests.

Why You’ll Love This Recipe

This dish is all about creamy layers, savory flavor, and contrast in textures. The potatoes soak up the cream and fish juices as they bake, becoming soft and flavorful, while the crispy topping adds a satisfying crunch. Everything bakes in one skillet, making cleanup easy. It’s also versatile—use your favorite white fish, swap in onions for leeks, or experiment with herbs for extra flavor.

Ingredients

(Tip: You’ll find the full list of ingredients and measurements in the recipe card below.)

For the Fish:

• 4 white fish fillets (about 5 oz or 160g each), skinless — barramundi, cod, snapper, tilapia, or salmon

• ½ teaspoon kosher salt

• ¼ teaspoon black pepper

For the Potato Gratin:

• 3 tablespoons unsalted butter

• 2 large leeks (white and pale green parts only), halved and sliced (or 2 onions)

• 3 garlic cloves, minced

• 2 medium starchy potatoes (about 8 oz or 250g each), peeled and sliced 1/6″ thick

• ¾ teaspoon kosher salt

• ½ teaspoon black pepper

• ½ cup low-sodium vegetable stock

• 1 cup heavy cream

For the Crunchy Topping:

• ¾ cup panko breadcrumbs

• 2 tablespoons extra virgin olive oil

• ¼ cup finely shredded parmesan cheese

Directions

1. Preheat Oven:
   Preheat to 350°F (180°C), or 320°F (160°C) for fan-forced ovens.

2. Prep Potatoes:
   Peel and thinly slice the potatoes. Soak them briefly in cold water to remove excess starch, then drain well.

3. Make Crunchy Topping:
   In a small bowl, mix panko breadcrumbs with olive oil, then stir in parmesan. Set aside.

4. Season Fish:
   Pat fish dry and season both sides with salt and pepper.

5. Cook Leeks and Garlic:
   In a large ovenproof skillet (12-inch), melt butter over high heat. Add leeks and garlic, and sauté for 3 minutes until softened.

6. Add Potatoes:
   Stir in the sliced potatoes, salt, and pepper. Cook for 6 minutes, stirring often, until potatoes begin to soften.

7. Simmer Stock:
   Add vegetable stock and let simmer for about 1½ minutes until slightly reduced.

8. Add Fish and Cream:
   Turn off the heat. Nestle seasoned fish fillets on top of the potatoes, presentation side up. Pour heavy cream over everything.

9. Add Topping and Bake:
   Sprinkle the prepared panko-parmesan topping over the fish. Transfer skillet to the oven and bake for 30 minutes.

10. Broil for Crispiness:
    Switch to broil on high. Move the skillet to the top oven rack and broil for 4 minutes, or until the topping is golden and crisp.

11. Rest and Serve:
    Let the dish rest for 5 minutes before serving. Scoop out portions that include both fish and creamy potatoes.

Servings and timing

Servings: 4
Prep Time: 10 minutes
Cook Time: 45 minutes
Total Time: 55 minutes

Variations

• Different Fish: Try salmon for a richer version or haddock for a lighter one.

• Cheese Upgrade: Use gruyère or aged cheddar in place of parmesan for a deeper flavor.

• Extra Veggies: Add spinach, thin zucchini slices, or mushrooms to the potato layer.

• Herb Boost: Stir fresh thyme, dill, or parsley into the gratin before baking.

• Spicy Touch: Add a pinch of chili flakes or a spoonful of mustard to the cream.

• No Cream Option: Substitute with half-and-half or a mix of milk and stock for a lighter dish.

• Gluten-Free: Use gluten-free breadcrumbs or omit the topping altogether.

• Onion Swap: Use onions instead of leeks if needed—sweet, yellow, or even shallots.

• Individual Servings: Divide into small baking dishes for personal gratins.

• Lemon Finish: Add a squeeze of fresh lemon over the fish just before serving for brightness.

Storage/Reheating

Storage:
Store leftovers in an airtight container in the refrigerator for up to 3 days.

Reheating:
Reheat gently in a 325°F (160°C) oven, covered with foil, until warmed through (about 15–20 minutes). For a crisp topping, remove foil for the last 5 minutes.

Freezing:
Not recommended, as the cream and potatoes can change texture after thawing.

FAQs

Can I use frozen fish for this recipe?

Yes, just thaw it completely and pat dry before using to avoid excess moisture.

What kind of potatoes are best for gratin?

Starchy potatoes like russets or Yukon Gold work best for a creamy texture.

Can I make this ahead of time?

Yes, assemble everything except the topping. Refrigerate, then add the topping and bake when ready.

Do I need a cast iron skillet?

Any oven-safe skillet or baking dish (about 12 inches) will work.

Can I use milk instead of cream?

Yes, but the gratin will be less rich. Whole milk or half-and-half are better substitutes than skim.

How do I know when the fish is cooked?

The fish should flake easily with a fork and be opaque all the way through.

What if I don’t like leeks?

Swap with onions or shallots for a similar flavor base.

Is this dish gluten-free?

Not by default. Use gluten-free panko or skip the topping to make it gluten-free.

Can I make it vegetarian?

Yes—omit the fish and layer in hearty vegetables like roasted cauliflower or sautéed mushrooms instead.

What sauce pairs well with this?

It doesn’t need much, but a dollop of lemon aioli or a light herbed yogurt sauce complements it well.

Conclusion

Creamy Fish on Potato Gratin is the ultimate cozy dish—simple to make, deeply satisfying, and packed with savory flavor. The combination of tender fish, rich cream, sweet leeks, and crisp topping makes it feel indulgent while staying balanced and light. Whether you serve it for guests or a quiet dinner at home, it’s guaranteed to impress.

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