Heat oil in a large skillet. Place flour in a large ziploc bag. Working with half of the chicken at a time, place chicken in the ziplock bag and shake to coat with flour. Fry the coated chicken in the hot oil for 3-4 minutes per side until golden brown on the outside. Repeat with remaining chicken. Place browned chicken in the bottom of the crock pot.
Turn the heat down to medium and deglaze the skillet by pouring the wine into the pan and stirring to loosen the browned bits from the bottom. Boil the wine for 4-5 minutes to reduce.
Cover chicken with onions and mushrooms. Pour reduced wine and chicken broth over the mushrooms and onions. Add minced garlic, thyme, salt, and pepper. Cover crock pot and set heat to low for 3 hours.
After 3 hours remove chicken thighs from crock pot and cover with foil. In a small bowl mix cornstarch and water and stir into the liquid in the crock pot. Turn heat to high and leave for 30 minutes until thickened. Stir in half and half cream and return chicken thighs to crockpot. Serve over mashed potatoes, rice, or noodles.
You can skip the step of removing the chicken from the crockpot before thickening the sauce, but you will end up with shredded chicken instead of whole thighs.
Store leftovers in the fridge for up to four days.
To reheat, gently rewarm chicken in a large skillet on the stovetop over medium-low heat. You can also reheat this dish in the microwave.