Prepare the Potatoes: Preheat your oven to 375°F (190°C). Place the sliced potatoes in a large baking dish. Drizzle with olive oil, season with salt and pepper, and toss to coat. Bake for 25-30 minutes, or until the potatoes are tender and lightly golden, stirring halfway through for even cooking.

Cook the Cod: While the potatoes are baking, season the cod fillets with salt, pepper, and a little olive oil. In a large skillet over medium-high heat, sear the cod fillets for 3-4 minutes per side, or until they’re golden and cooked through. Remove from the skillet and set aside.

Make the Rosemary Cream Sauce: In the same skillet, add a little more olive oil if needed. Sauté the chopped onion for about 2-3 minutes until softened. Add the garlic and chopped rosemary, cooking for another minute until fragrant.

Add the Cream and Broth: Pour in the heavy cream and chicken broth, stirring to combine. Let it simmer for 3-5 minutes, allowing the sauce to thicken slightly. Taste and adjust seasoning with salt, pepper, and optional lemon zest.

Combine the Cod and Potatoes: Once the potatoes are cooked, layer them in the baking dish with the seared cod fillets. Pour the rosemary cream sauce over the cod and potatoes, making sure everything is covered.

Finish in the Oven: Bake everything together for an additional 10-15 minutes, or until the sauce is bubbly and everything is heated through. If you’d like, you can add a tablespoon of butter to the sauce just before baking for extra richness.

Serve: Garnish with fresh parsley before serving. Serve your cod and potatoes in rosemary cream sauce with a side of steamed vegetables or a crisp green salad.