Season the chicken thighs generously with salt and pepper.
Heat oil in a skillet over high heat, then brown the chicken on both sides before setting it aside and draining any excess oil.
In the same pan, cook the bacon over medium heat until the fat begins to render.
Add the onions and garlic, stirring for about five minutes until the onions soften and the bacon turns crispy at the edges.
Stir in the mushrooms, additional salt, pepper, and dried herbs, cooking until the mushrooms are browned.
Pour in the white wine and chicken stock, then add the sage and bay leaves.
Return the chicken to the pan, bring everything to a gentle simmer, and transfer to a preheated 160°C (325°F) oven.
Cover and cook for 20 minutes, then uncover and cook for another 10 minutes.
Alternatively, simmer on the stove over low heat for about 20 minutes until the chicken is fully cooked.
Stir in the crème fraîche and, if needed, thicken the sauce with xanthan gum or a little diluted cornflour, allowing it to simmer briefly.
In a separate pan, melt butter and fry the sage leaves until crispy, then drain them on a paper towel.
Discard the bay leaves, adjust the seasoning, and serve topped with crispy sage leaves alongside mashed potatoes or a low-carb alternative.