• Clarify the butter in a small pan by gently melting over a low heat. When the butter has melted, the milk solids will have dropped to the bottom of the pan. Very very gently, pour the clarified butter into a small jug and discard the solids.

Gratin potatoes

• Preheat the oven to 140C fan. Peel the potatoes and slice to approx 2mm thick, ideally using a mandolin. Any starch that leaches out of the potatoes should be kept as that is going to help thicken the milk.
• Put the milk and cream in a large pan and bring to a simmer. Generously season with salt and pepper then slid in the potato slices making sure each slice is coated with the milk and add any collected starch juice. Simmer on a low heat for 10 minutes, stirring to prevent sticking to the bottom of the pan.  Remove from the heat and stir in the grated cheese add more salt if necessary.
• But the garlic in half lengthways, rub a small roasting tin or casserole dish with the cut side of the garlic then discard. Tip in the potatoes and smooth out with a spatula. Bake in the oven for 50 minutes or until soft when pierced through with a knife. Leave to rest for 10 minutes while you finish the beans and cook the fish.

Bacon beans

• Bring a pan of salted water to the boil. Add the halved pieces of garlic and allow to infuse into the water for 5 minutes. Cook the beans for 5 minutes then drain and pick out the pieces of garlic return to the pan, drizzle with a little olive oil and season if necessary, put the lid on to keep warm and set aside until ready to serve

Cooking the fish and finishing the dish

• In a nonstick pan on a medium heat, add the clarified butter, pat any excess moisture from the fish fillets, season well with salt and pepper, once the butter is frothy, add the fish skin side down and cook for 4 minutes using a spatula to press the fish flat onto the pan to ensure the skin becomes lovely and crisp. Turn the fish over and cook for 2-3 more minutes depending on the thickness. Remove from the heat and allow rest in the pan for a couple of minutes.
• Divide the beans between 4 warmed dinned plates, add a slice of gratin potatoes to each plate, place the cod skin side up on top of the beans and finish with a sprinkle of chives.