Pat the chicken dry with paper towels. Season all sides with 1½ teaspoons of the kosher salt and ½ teaspoon of the black pepper.
Heat 2 tablespoons of neutral oil in a large Dutch oven over medium-high heat.
Working in batches, brown the chicken for 3–4 minutes per side. The chicken does not need to cook through. Transfer the browned pieces to a plate and reduce the heat to medium.
Carefully add ¾ cup neutral oil to the pot. Sprinkle in the flour and stir until smooth.
Cook the roux over medium to medium-low heat for 18–25 minutes, stirring constantly. Scrape across the bottom and into the corners of the pot until the roux reaches a deep copper or milk-chocolate color.
Carefully stir the onion, green bell pepper, and celery into the finished roux. Cook for 6–8 minutes, stirring frequently, until the vegetables begin to soften.
Add the garlic, paprika, garlic powder, onion powder, and cayenne. Cook for 1 minute, stirring constantly.
Slowly pour approximately 1 cup of the warm chicken broth into the roux while whisking continuously. Once the mixture is smooth, gradually whisk in the remaining broth.
Stir in the Worcestershire sauce, thyme, bay leaves, optional hot sauce, remaining ½ teaspoon kosher salt, and remaining ½ teaspoon black pepper.
Bring the gravy to a gentle simmer. Return the browned chicken and any accumulated juices to the pot. The gravy should reach most of the way up the chicken without completely covering it.
Reduce the heat to low and cover the pot. Simmer gently for 40 minutes, turning the chicken once during cooking.
Partially uncover the pot and continue simmering for 15–20 minutes, or until the chicken is tender and the thickest pieces have reached at least 165°F.
If the gravy is too thin, transfer the chicken to a platter and simmer the gravy uncovered for 5–10 minutes. If it is too thick, gradually add a small amount of warm broth or water.
Remove and discard the bay leaves. Stir in most of the parsley and green onions. Taste the gravy and add more salt if needed.
Return the chicken to the gravy. Remove the pot from the heat and allow the fricassee to rest for 10 minutes.
Garnish with the remaining parsley and green onions. Serve the chicken and dark roux gravy over hot white rice.