In a large skillet, heat olive oil and butter over medium-high heat until shimmering. Add chicken breasts and sprinkle with salt and pepper.
Cook chicken breasts 4 - 5 minutes per side or until meat thermometer registers 165° F and chicken is done. Remove breasts to a large plate. Set aside.
Drain all but 1 TBSP drippings from the pan. Add garlic and cook until fragrant, about 1 minute. Add wine and to skillet, scraping brown bits from bottom of pan. Simmer until reduced by half, about 4 minutes. Add chicken stock and thyme to pan. Bring mixture to a boil. Add cream, Dijon and stone ground mustard. Stir to combine, and bring to a simmer. Sauce will start to thicken.
Add chicken back to the pan and cook additional 3 - 4 minutes until chicken is heated thru.
Serve chicken with sauce spooned on top.
Slice chicken breasts in half lengthwise for faster cooking time.