Place a sheet of baking paper on your chopping board. Lay the chicken breasts on top, cut them in half, and cover with another sheet of baking paper. Use a mallet to gently flatten the chicken until even.

In a bowl, combine plain flour with a pinch of salt and pepper and mix. Lightly coat each chicken piece in the seasoned flour, shaking off any excess.

Heat a large pan over medium-high heat. Add a generous amount of EVOO and half the butter. Once the butter melts, add the chicken pieces.

Season with a little salt and pepper, then cook for 2 minutes on each side, or until golden brown. Turn off the heat and transfer the chicken to a plate lined with paper towels to rest.

Clean the pan by removing any leftover burnt bits, but leave the sauce which has been created. Add more EVOO, turn the heat up to medium, and add the crushed garlic. Sauté until lightly golden, then add the sliced mushrooms to the pan and stir to combine. Remove the rosemary leaves from their sprigs and add them to the pan. Stir again.

Pour in ½ cup Marsala wine and season with a pinch of salt and pepper. Cook for 5–7 min, stirring occasionally, until the alcohol evaporates or the liquid reduces slightly, then add half a glass of vegetable stock, cover with a lid and let it simmer for another 5 minutes, stirring occasionally.

After 5 minutes, remove the lid. Sprinkle a small pinch of flour into the sauce, and stir to thicken. Add the remaining butter and return the chicken to the pan. Pour a little more Marsala over the chicken, turning each piece to coat it fully in the sauce. Once the chicken is evenly covered and the sauce is glossy, turn off the heat and serve immediately.