Season the chicken thighs with the SP&C, paprika, parsley flakes, and hot sauce.

Melt 3 tablespoons of butter in a 5-quart cast iron Dutch oven.

Brown the chicken thighs in batches, adding additional butter or oil, if necessary.

Place browned chicken thighs on a paper towel-lined plate.

Deglaze Dutch oven with 1/3 cup gluten free chicken broth, ensuring that your spoon picks up all of the browned bits at the bottom.

Add 3 more tablespoon of butter and the onions to the Dutch oven. Stir until well-incorporated.

Cook the onions down for about 30 minutes, or until caramelized to your liking. (You may need to add more butter if the onions start to stick to the pot.)

While the onions are cooking down, place the celery, green bell pepper, Worcestershire sauce, hot sauce, and 2 tablespoons chicken broth in a blender. Pulse until liquefied.

When the onions are caramelized, add the blender mixture to the onions. Stir until well-incorporated, then let cook for about 2 minutes to let the flavors combine.

Add the chicken and remaining gluten free beef broth and chicken broth to the pot.

Stir until combined.

Cook for 30 minutes, tasting and adjusting seasonings half-way through, if desired.

Preheat broiler.

Toast the Udi's buns, then place cheese on top.

Broil for 1 to 2 minutes,or until the cheese is melted and bubbly.

Serve 1/2 of bun with each bowl of soup.