Cook the potatoes

• Peel and cut the potatoes, then boil them in salted water until tender.
• Mash with a little butter and season to taste.

Sear the buttered chicken

• Season the chicken with salt and pepper.
• Melt half of the butter with the olive oil in a frying pan and sear the chicken until golden and cooked through.
• Add the rosemary sprigs and baste the chicken with the foaming butter, then set aside.

Sauté the mushrooms

• In the same pan, melt the remaining butter and cook the onion until soft.
• Add the mushrooms and cook until golden and their moisture has evaporated.
• Stir in the garlic and cook until fragrant.

Make the creamy sauce

• Pour in the cream and bring to a gentle simmer.
• Stir in the grated parmesan and season with salt and pepper.
• Simmer until the sauce thickens slightly.

Serve

• Return the chicken to the pan and coat with the mushroom sauce.
• Serve with the mashed potatoes.