Preheat your Yoder Smokers YS640s Pellet Grill to 450ºF, set up for direct grilling (diffuser door or entire diffuser plate removed).
Place a Lodge 7 Quart Enameled Dutch Oven inside the grill to preheat for at least 5 minutes.
Break the chicken down into 8 pieces. Season generously with Cattleman’s Grill Italiano Seasoning, then dredge in flour to coat the surface.
Position the dutch oven directly over the flame. Add one tablespoon each of butter and oil.
Sear the chicken in the dutch oven, working in batches so as not to overcrowd the cast iron. When the chicken is golden brown on all sides, remove from the dutch oven.
The remaining one tablespoon each of butter and oil. Add the mushrooms and shallots. Cook until they being to soften, about 3-5 minutes.
Add the wine and allow to reduce almost entirely (au sec).
Add the garlic and tomatoes. Cook for about 30 seconds.
Add the chicken stock and heavy cream. Stir gently. Return all of the chicken to the dutch oven. Close the lid of the grill and allow to cook until the chicken reaches an internal temperature of 165ºF, about 10-15 minutes.
Remove the chicken from the dutch oven. Add the spinach and cook until wilted. Return the chicken to the dutch oven and serve warm over pasta or potatoes.