Sautéing the chicken: Heat the oil in a large skillet over medium high heat. Season chicken with salt, pepper and Italian seasoning on both sides. Cook the chicken on medium high skin side down first until golden brown, then flip over and cook on the other side, 4 to 5 minutes per side; transfer chicken to a plate. Chicken will not be cooked through at this point.
Add 1 tablespoon butter to the now empty skillet that has fats from chicken and olive oil. Add chopped garlic and cook for 2 minutes until fragrant. Add flour. Stir to create a paste. Cook for 1 minute. Add wine and cook until it reduces a bit. Add chicken broth. Whisk in heavy cream and Dijon mustard until well incorporated. Add salt and fresh thyme leaves. Cook, whisking constantly, for 2 to 3 minutes or until mixture thickens and becomes smooth. Remove from heat.
Preheat oven to 400 F.
Add removed chicken back to the skillet with sauce. Surround it with potatoes. I didn't spoon the sauce over the chicken in order to ensure proper browning during baking process. Add more fresh thyme sprigs and fresh rosemary on top of chicken and potatoes. Cover with foil or lid.
Put the skillet with chicken into the oven covered and bake at 400 F for 50 minutes. Increase temperature to 425 F, uncover and continue cooking for 10 more minutes until chicken is dark brown. Check to make sure chicken is cooked all the way through. Stand 5 minutes. If desired, remove rosemary and thyme sprigs before serving. Serve sprinkled with extra thyme.