Place chicken pieces into a large mixing bowl with one cup of buttermilk. Toss to coat all of the chicken with the buttermilk. Place into the refrigerator for one hour.

Prepare the dredge mixture to a large mixing bowl by combining the flour and seasoning together. For this particular dish, I do not do the standard - dry, wet, dry - dredge. You don't need an extra crispy fried chicken for smothered chicken. You just want it to have a coating to hold onto the gravy. The brown bits left in the skillet also add lots of flavor to the gravy preparations.

Take each piece of buttermilk coated chicken and add it to the bowl with the dredge mixture. Toss to coat. Shake off any excess flour and set aside for frying. Be sure to reserve the leftover dredge mixture. We are going to use that in the gravy and it's already seasoned beautifully.

Preheat oven to 350℉

Add vegetable oil to a large cast iron or metal skillet and warm over medium heat. When the oil is hot for frying add the dredged chicken pieces. You may have to cook the chicken in batches so each piece has plenty of room for browning.

Cook each piece of chicken about four minutes per side until the coating is nicely browned. The chicken does not have to be cooked through at this point. It will finish cooking in the oven. Once browned remove the chicken pieces and place into a large casserole dish.

Add the onions and mushrooms to the skillet and saute for three minutes to soften.

Sprinkle in the reserved dredge mixture and toss to coat with the vegetables and remaining cooking oil. Cook four to five minutes.

Add chicken stock to the skillet and stir to combine with the vegetables. Be sure to scrape any brown bits from the chicken off the bottom of the skillet. I had to pull out my wire whisk for this. Continue to cook until the gravy thickens.

Pour the gravy over the chicken in the casserole dish.

Cover with foil and place the casserole dish into the oven. Bake for 1.5 to 2 hours.