Preheat your oven to 325°F (163°C). Pat the chicken pieces dry and place them on a plate. In a small dish, combine 2 teaspoons of the kosher salt and 1/2 teaspoon of black pepper. Rub this mixture all over the chicken, including under the skin for maximum flavor.
In a 3 to 5 quart Dutch oven, melt the butter over medium-high heat. Add the seasoned chicken pieces, browning them on both sides for about 3 to 5 minutes per side. Once browned, remove the chicken from the pot and set it aside on a plate.
Add the halved mushrooms, chopped shallots, diced celery, and minced garlic to the Dutch oven. Stir to coat the vegetables in the remaining butter, letting the mushrooms soak up the liquid and then release their juices. Then, season with the remaining 1 teaspoon kosher salt, 1/2 teaspoon black pepper, and add the minced sage and parsley. Sauté until the mushrooms are softened and the shallots are translucent, about 7 minutes. I love how aromatic this step makes the kitchen!
Sprinkle the flour over the sautéed vegetables and toss to coat evenly. Pour in the dry white wine to deglaze the pot, scraping the bottom to loosen any browned bits. Gradually pour in the chicken stock, about 1 cup at a time, stirring as you go to help the sauce thicken. Bring the sauce to a boil and allow it to cook until it reaches the consistency of a thin gravy, about 5 minutes.
Add the halved baby potatoes to the sauce and stir to coat. Nestle the browned chicken pieces (from Step 2) on top of the vegetables and sauce. Transfer the entire pot, uncovered, to the preheated oven. Roast for 40 to 45 minutes, or until the chicken has reached an internal temperature of 165°F (74°C). For extra flavor, I sometimes add a few fresh herb sprigs on top before baking.
Remove the pot from the oven and stir in the cream. Cover with a lid or tent with foil, and let the dish rest for at least 10 minutes before serving. This resting period helps the flavors meld, and ensures the chicken stays juicy.
Serve the dish hot, making sure each serving gets pieces of chicken, potatoes, mushrooms, and plenty of the luscious wine sauce.