Season the chicken thighs with salt and pepper on all sides. In a large bowl or plate coat the chicken thighs in cornstarch. Shake off/discard any leftover cornstarch on the plate.
In a large nonstick skillet heat cooking oil over medium-high heat. Once the oil is hot sear the chicken thighs for 6 minutes on both sides. The exterior should crisp up and become golden brown.
Reduce the heat to medium-low, cover the skillet with a lid and cook the chicken for an additional 12 minutes
In the same skillet melt the butter, and add the sliced mushrooms. Cook constantly stirring for about 4 minutes and add Italian herbs and garlic. Make sure the garlic gets slightly brown.
Cook for additional 30 seconds to 1 minute. Deglaze the pan with chicken stock and simmer for 3 minutes. Make sure the heat is on medium-low and slowly pour in the cream.
Let the cream simmer for a minute or so before adding the parmesan. Stir the sauce until the parmesan is melted and the sauce thickened. Taste for seasoning and add salt and black pepper accordingly.
Return the cooked chicken thighs and coat in the sauce. Let them simmer in the sauce for 3-5 minutes. Garnish with parsley and more parmesan.