Liberally season the chicken on both sides with salt and pepper. In a large, deep, heavy skillet with a fitted lid large enough to fit all the chicken thighs in one layer, heat 1 tablespoon each of olive oil and butter.

Once hot and the butter is beginning to foam, place the chicken, skin-side down, in the skillet.

Cook for 10-15 minutes, or until deeply browned (the chicken should easily release from the bottom of the pan when done; if it sticks, it is not yet ready). Remove the chicken from the pan, and set aside on a platter.

Heat the remaining tablespoon olive oil and 1 tablespoon butter in the skillet (do not wash it out first). Add the mushrooms, stir to coat, and allow to cook, undisturbed, for at least 3 minutes or until well-browned. Season with salt and pepper, stir, and allow to cook for a further 3-5 minutes, until most of the water has cooked out.

Add the remaining tablespoon butter, and once it has melted, add the onions, cooking until browned. Turn the heat down to medium, stir in the garlic, and sauté for another minute. Add the rice and stir, scraping up any fond from the bottom of the pan, for about 2 minutes, allowing it to toast.

Add the Marsala wine, and cook until mostly absorbed. Add the chicken stock and return the chicken—skin-side up—to the pan, along with its juices, allowing it to rest upon the rice. Bring the stock up to a boil and cover, cooking at about medium heat (the stock should be at a simmer) for 25-35 minutes, until the rice is tender and chicken is cooked through.

If the broth has evaporated and the rice is not yet done, add more stock, a ladleful at a time, until the rice is fully cooked.

Top with fresh parsley, and serve hot.