Wash the baby potatoes thoroughly, then halve or quarter them for quicker cooking. In a large pot, bring salted water to a boil and add the potatoes. Cook for about 8–10 minutes, or until they are fork-tender but not mushy. Once cooked, drain the potatoes and set them aside.

While the potatoes are cooking, pat the cod fillets dry with a paper towel. Season them with salt, pepper, lemon juice, and lemon zest. Allow to marinate for 5-10 minutes.

In a large skillet, heat olive oil and butter over medium-high heat. Add the marinated cod fillets and sear for 3–4 minutes on each side until golden brown. Transfer to a plate and cover loosely with foil.

Lower heat to medium and add more olive oil if necessary. Sauté finely minced garlic and chopped shallots for 2–3 minutes until fragrant. Stir in chopped rosemary.

Pour in the halal-certified broth, bringing to a simmer while scraping up browned bits. Slowly stir in heavy cream and optional Dijon mustard. Cook for 6–8 minutes until thickened.

Add the drained potatoes into the sauce, gently tossing to coat. Simmer for 3–4 minutes, allowing the potatoes to absorb flavors.

Return the seared cod to the skillet, spooning sauce over it. Simmer together on low for an additional 2–3 minutes.

Serve hot, garnished with fresh parsley or chives.