Ingredients

4 x 160g (5oz) white fish fillets, skinless and about 2cm (0.8″) thick (barramundi, snapper, tilapia, cod, or salmon)

1/2 tsp cooking or kosher salt

1/4 tsp black pepper

3 tbsp (50g) unsalted butter

2 large leeks (white and pale green parts only), washed and sliced 5mm (0.2″) thick, or 2 onions

3 garlic cloves, minced

2 medium starchy potatoes (about 250g / 8oz each), peeled

3/4 tsp cooking or kosher salt

1/2 tsp black pepper

1/2 cup dry white wine (any type, or substitute more vegetable stock)

1/2 cup low sodium vegetable stock or broth

1 cup thickened or heavy cream

3/4 cup panko breadcrumbs

2 tbsp extra virgin olive oil

1/4 cup finely shredded parmesan

Instructions

Step 1: Preheat your oven to 180°C (350°F) or 160°C fan, placing a shelf in the middle.

Step 2: Cut the potatoes into quarters and then slice them about 4mm (1/6″) thick. Place the slices in a large bowl of water to prevent browning and remove excess starch, then drain before use.

Step 3: In a bowl, combine the panko breadcrumbs and olive oil, then stir in the parmesan to create the crunchy topping.

Step 4: Season both sides of the fish fillets with salt and pepper. Set them aside.

Step 5: Melt the butter in a large oven-proof skillet (about 30cm/12″) over high heat until foamy. Add the leeks (or onions) and garlic, cooking for 3 minutes until soft.

Step 6: Add the drained potatoes, salt, and pepper to the skillet. Cook, stirring regularly, for 6 minutes until the potatoes are half-cooked.

Step 7: Pour in the white wine and simmer rapidly until mostly evaporated, about 1 minute. Add the vegetable stock and simmer for 1 1/2 minutes until reduced by half.

Step 8: Turn off the stove and place the fish fillets on top of the potatoes, presentation side up. Pour the cream evenly over everything and sprinkle the prepared panko and parmesan topping on top.

Step 9: Bake in the oven for 30 minutes. This ensures the fish stays moist and the flavors meld beautifully.

Step 10: Switch your oven to grill (broil) on high and move the skillet to the top shelf. Grill for about 4 minutes until the topping turns golden and crunchy.

Step 11: Remove the skillet and let the dish rest for 5 minutes before serving. For the best taste, enjoy each bite of fish and gratin together.

Tips & Variations

Choose starchy potatoes like Russets or Yukon Gold for a creamy texture that absorbs flavors well.

Substitute the leeks with onions if you prefer a sharper flavor or don’t have leeks on hand.

You can replace white wine with extra vegetable stock to keep the dish alcohol-free.

For added freshness, garnish with chopped parsley or chives before serving.

FAQs

Can I use frozen fish for this recipe?

Yes, you can use frozen fish fillets. Make sure to thaw them completely and pat dry before seasoning and cooking to avoid excess moisture in the dish.

What type of fish works best?

Firm, white fish like barramundi, snapper, tilapia, or cod are ideal because they hold their shape during cooking. Salmon can be used but will lend a stronger flavor and a different texture.