Pre-heat oven to 375°F.

Heat a large sauté pan or skillet over medium-high heat. Generously season the chicken thighs with salt and freshly ground black pepper. Add a good glug of olive oil and 1 tablespoon of the butter to the pan. Brown the chicken thighs for 3 to 4 minutes on both sides. Transfer the browned chicken to a plate and set aside.

Add the cipollini onions to the pan and sauté for 5 to 7 minutes, stirring often, until the onions are well browned all over. Deglaze the pan with the marsala wine, scraping up any brown bits on the bottom of the pan. Add the chicken stock, bring to a simmer and then reduce the heat in the pan and simmer until the liquid has reduced by half. Season the sauce with salt and freshly ground black pepper to taste. Return the chicken and any of its juices to the pan and spoon the sauce over the chicken thighs. Tear up the slices of the prosciutto and scatter it over the chicken and sauce. Transfer the pan to the oven for 15 to 20 minutes, until the chicken reaches an internal temperature of 165°F on an instant read thermometer inserted into the thickest part of the thigh.

Remove the pan from the oven (remember the handle will be hot). Swirl the remaining tablespoon of butter into the sauce and squeeze the lemon juice over the chicken. Sprinkle the chopped parsley on top.

Serve with some rice or mashed potatoes and a green vegetable or salad.