Cheese & bacon Hasselback potato bake

Preheat the oven to 200ºC, gas mark 6. Grease a shallow 30cm round cast iron or ovenproof dish (or a 30x25cm roasting tin) with the butter and set aside. Place the onion and bacon into a cold, dry frying pan and cook over a medium heat for 10 minutes, stirring occasionally, until the bacon is crisp and the onion soft. Remove to a large bowl and leave to cool slightly.

Meanwhile, place the potatoes one at a time, between the handles of two wooden spoons or chopsticks. Using a sharp knife with a thin blade, cut all the way along the potato into thin vertical slices (about 2-3mm thick) without cutting all the way through – the spoon handles/chopsticks will help achieve this – so the slices are still attached at the base. Repeat with all the potatoes.

Mix the bacon and onion in the bowl with the garlic, parmesan, cream, thyme and salt. Season with black pepper. Tip into the prepared dish, then put the potatoes on top, turning them in the cream mixture until well coated.

Position the potatoes, cut-sides up, in a single tightly packed layer. Cover with foil and bake for 1 hour, then remove the foil and cook for another 20-25 minutes, pushing the mozzarella in between the potatoes for the last 10 minutes, until golden and bubbling. Remove and leave to rest for 5-10 minutes before serving scattered with extra thyme, if using.