Season the chicken pieces all over with salt and the red pepper flakes.
Heat the oil in a large skillet over medium-high heat.
Add the chicken to the skillet in a single layer, skin side down, and lower the heat to medium and sauté for about 8 minutes, until the have browned nicely on the bottoms.
Flip the chicken pieces and sauté for another 8 minutes.
Transfer the chicken to a rimmed baking sheet, or platter, and set aside.
In the same skillet, add the onions and cook until they have softened, about 5 minutes.
Add garlic and mushrooms and cook over medium-high heat, until the mushrooms are releasing their liquid and becoming slightly browned on the edges.
Pour in the white wine and simmer until almost all of the liquid is gone, about another 5 minutes.
Season with a nice pinch of salt and then add the tomatoes with their juices and bring to a simmer.
Nestle the chicken pieces along with any accumulated juices into the simmering sauce and then nestle in the bay leaves and thyme (hold off on the rosemary).
Turn the heat to low and simmer for 45 minutes. Add the rosemary after the dish has simmered for about half an hour (allowing the rosemary to simmer for a total of approx. 15 minutes).
Remove the pan from the heat and let rest for about 10 minutes.
Taste and add more salt, if desired.
Plate chicken pieces with sauce poured over the top.