Season the chicken thighs generously with salt and pepper on both sides.
In a large skillet, heat olive oil over medium-high heat until shimmering.
Place chicken thighs skin-side down in the skillet and cook for 5-7 minutes until golden brown. Flip and cook for an additional 5 minutes. Remove from skillet and set aside.
In the same skillet, reduce heat to medium and add minced garlic. Sauté for 1-2 minutes until fragrant.
Pour in chicken broth, scrape up brown bits, then stir in heavy cream, thyme, parsley, Dijon mustard, and lemon juice. Bring to a simmer.
Return chicken thighs to the pan, skin-side up. Reduce heat to low, cover, and let simmer for 15-20 minutes until cooked through.
If desired, remove chicken and let the sauce simmer uncovered for a few minutes to thicken.
Return the chicken to the skillet, spoon the sauce over, and garnish with fresh parsley and grated parmesan if desired.