Add butter and onion to the skillet.
Cook for 1 to 2 minutes, until the onion is soft.
Add the garlic. Cook for 1 minute.
Pour the chicken stock, oregano, thyme, and 4 tablespoon Dijon mustard.
Mix with a spatula.
Gently scrape the browned bits on the bottom of the skillet.
Return the chicken to the skillet. Reduce the heat to medium-low.
Cover and cook for 20 minutes.
Turn the chicken after 10 minutes.
Mix the cornstarch with water.
Stir in the heavy cream, the cornstarch mixture, and salt to the skillet.
Mix to combine.
Bring to a simmer. Simmer for 2-3 minutes, or until the sauce thickens.
Taste for salt. Adjust if necessary.
Serve with rice and veggies. Enjoy!