Mix the salt pepper and garlic into the flour. Dredge each chicken thigh in the flour mixture.
Heat the olive oil and 1 tablespoon of the butter in a skillet over medium-high heat. Once the pan is hot, add the chicken and sear it for 4-5 minutes/side or until golden. Take the chicken out of the pan and set aside (it'll finish cooking in the sauce).
Add the remaining butter and mushrooms to the skillet and cook them for 3-5 minutes, stirring occasionally, until browned.
Add the minced garlic and marsala wine to the skillet and let it bubble for 2-3 minutes.
Add the cream to the skillet, and then add the chicken back in. Cook for another 4-5 minutes until the chicken is cooked through and the sauce has thickened up a bit. Season with extra salt & pepper if needed.