Preheat your oven to 350 degrees F.
In a small bowl, combine the paprika, Italian seasoning, garlic powder, and onion powder. Trim off any excess chicken fat and then season the chicken with salt, pepper, and the spice blend on both sides and under the skin. Be careful not to tear the chicken skin.
Heat the oil in a large pot over medium-high heat. Add the chicken to the pot skin side down and cook for 3-4 minutes on each side. Work in batches if you have to.
Remove the chicken from the pot and set it aside.
Add the onions and celery and cook for 1 minute. Stir in the garlic, tomato paste, and red crushed pepper flakes. Cook for 15 seconds.
Stir in the flour and cook for 1-2 minutes. Add the chicken stock, rosemary, thyme, and Worcestershire sauce. Season the broth with salt and pepper.
Place the chicken back into the pot skin-side up, keeping the skin above the liquid. Bring to a simmer then cover and place it in the oven for 45 minutes.
Once the 45 minutes are up, uncover and cook for 20 minutes. Once the 20 minutes are up, add the butternut squash, pushing them into the liquid. Cook for 25 minutes or until the broth is thickened and the butternut squash is fork-tender.
Remove the chicken from the pot, discard the rosemary and thyme sprigs, skim the fat off the stew with a ladle or spoon, check for seasoning and then place the chicken back into the pot.
Serve immediately and enjoy!