Season chicken with salt/pepper.
Heat 1 tablespoon olive oil in a large skillet over medium heat.
Once hot, Cook chicken skin side down for 15 minutes.
Turn chicken and add onions.
Cook another 15.
Transfer chicken to a plate leaving onions in pan.
Add mushrooms and cook a few mins.
Add wine, creme fraiche, Dijon mustard, whole-grain mustard, and 1 teaspoon salt to the skillet.
Stir for a minute.
Return chicken to pan.
Top with parsley.
Let simmer in sauce a few mins on low.
(If sauce too thick, you can thin with a little broth)