Season chicken pieces liberally with salt and pepper on both sides.
Heat olive oil in a skillet over medium heat. Add chicken to skillet and cook until browned all over, about 6-7 minutes each side, or until internal temperature reaches 165 degrees.
Remove chicken from skillet and set aside.
In the same skillet, melt butter over medium heat and add mushrooms. Sauté until golden brown and tender.
Add chopped spinach and garlic. Cook until spinach wilts
Pour in heavy cream, stirring constantly. Allow mixture to simmer for 2-3 minutes.
Add grated parmesan cheese and continue stirring until sauce thickens.
Season with salt and pepper.
Place the chicken thighs back into the skillet with the spinach mushroom sauce.
Spoon sauce over chicken to coat evenly.
Continue to simmer an additional 2-3 minutes to allow flavors to meld together.
Serve the chicken thighs with a generous ladle of spinach mushroom sauce on top.
Garnish with fresh chopped parsley for an added pop of color!