Baked Tilapia and Potato Gratin with Creamy Tomato Sauce

Name: Baked Tilapia and Potato Gratin with Creamy Tomato Sauce
Prep time: 30 min
Total time: 30 min
Yield: 8 servings
Cuisine: Française
Ingredients: 800 g (1¾ lb) waxy potatoes, peeled and sliced into rounds; 800 g (1¾ lb) tilapia fillets; 260 g (9 oz) tomato passata or crushed tomatoes; 250 g (1 cup) sour cream or crème fraîche; 200 g (7 oz) shredded mozzarella or emmental; 2 lemons; 2 garlic cloves, minced; 2 tbsp olive oil; 1 tsp dried Italian herbs or herbes de Provence; Salt and black pepper to taste

By Marie Lefebvre · Updated September 17, 2026

A hearty baked gratin featuring golden pan-seared tilapia fillets layered over tender potatoes, draped in sour cream and bubbling melted cheese. Simple enough for busy weeknights yet impressive enough to serve guests.

Prep⏱️ 30 min

Servings👥 8 servings

Difficulty📊 Easy

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🛒 Ingredients

8 servings

800 g (1¾ lb) waxy potatoes, peeled and sliced into rounds
800 g (1¾ lb) tilapia fillets
260 g (9 oz) tomato passata or crushed tomatoes
250 g (1 cup) sour cream or crème fraîche
200 g (7 oz) shredded mozzarella or emmental
2 lemons
2 garlic cloves, minced
2 tbsp olive oil
1 tsp dried Italian herbs or herbes de Provence
Salt and black pepper to taste

🛍️ Recommended tools

🫕Cocotte en fonteSee on Amazon →🔪Couteau de chefSee on Amazon →

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Directions

1
Preheat the oven to 200 °C / 400 °F. Boil the potato slices in salted water for 10 minutes until just tender; drain well.
2
In a skillet, warm 1 tbsp olive oil over medium heat and sauté the minced garlic for 1 minute. Add half the tomato passata and dried herbs; season with salt and pepper and simmer 3 minutes.
3
Arrange the drained potato slices in a greased baking dish. Spread the sour cream evenly over the top, then spoon the garlic tomato sauce over the cream layer.
4
Pat the tilapia fillets dry, squeeze lemon juice over them, season with salt and pepper, and let sit for 5 minutes.
5
In the same skillet with the remaining olive oil, pan-sear the fillets over medium-high heat for 2–3 minutes per side until lightly golden.
6
Place the seared tilapia fillets on top of the potato layer. Spoon the remaining tomato passata over the fish.
7
Scatter the shredded cheese generously over the top and bake for 20–25 minutes until the cheese is golden and the sauce is bubbling.
8
Rest for 5 minutes before serving with steamed rice or a green salad.

💡 Chef's Tip

Add a handful of pitted black olives or capers between the potato layers for a Mediterranean twist. Leftovers reheat beautifully in the oven at 180 °C for 10 minutes.