Make sure the chicken is thoroughly cleaned before starting. Brush or spoon the melted butter evenly over the chicken thighs, then rub it in with your hands to coat well. Season the chicken generously with seasoning salt, onion powder, poultry seasoning, garlic powder, ground black pepper, and smoked paprika. Lightly spray your baking dish or Dutch oven with non-stick spray, then arrange the chicken pieces inside. Spread the sliced onions evenly over the top of the chicken and cover the dish with a lid or foil. Bake in a preheated oven at 375°F (190°C) for 20 minutes.

After baking, remove the chicken from the oven and carefully reserve about 4 to 5 tablespoons of the chicken drippings. Pour these drippings into a pan on the stovetop and heat over medium-high heat. Once the drippings begin to bubble, gradually sprinkle in the all-purpose flour, adding just a little at a time to avoid clumps. Stir or whisk continuously until the flour mixture turns golden brown.

Reduce the heat to medium and slowly pour in the chicken broth while whisking constantly to create a smooth, lump-free gravy. The gravy may seem thin at this stage, but it will thicken as it cooks. Pour the gravy back over the chicken in the original baking dish.

Return the chicken to the oven uncovered and bake for another 20 minutes. During this time, baste the chicken with the pan gravy to keep it moist and flavorful. Then, bake uncovered for a final 10 minutes. Once done, let the dish rest for 5 minutes before serving. Enjoy your delicious smothered baked chicken with gravy