For the chicken: Whisk together the flour and House Seasoning in a large bowl. Add the chicken and toss to coat.
Add the oil to a large cast-iron skillet over medium-high heat. Remove the chicken from the flour mixture, shaking to remove any excess, and add to the hot oil. Fry until the chicken is golden brown on all sides, about 5 minutes per side. Remove to a plate and set aside.
For the sauce: Add the diced onions to the hot oil in the skillet and cook until the onions are slightly softened and translucent, 2 to 3 minutes. Add the butter, garlic, thyme and rosemary and cook until fragrant, about 1 minute more. Whisk in the stock, scraping up any bits from the bottom of the pan. Simmer until thickened, 3 to 4 minutes. Whisk in the cream, Dijon and ground mustard and bring to a simmer again until thickened, 2 to 3 minutes. Add the chicken, turning to coat with the gravy. Cover and cook, turning the chicken occasionally, 25 to 30 minutes. Sprinkle with the parsley before serving.
Yield: 1 1/4 cups
Stir together the garlic powder, onion powder, paprika, salt and pepper in a medium bowl. Keep in an airtight container for up to 6 months.