1. Marinate Chicken: In a bowl, combine the buttermilk, garlic powder, onion powder, smoked paprika, salt, and pepper. Add the chicken thighs, ensuring they are fully coated. Cover and marinate for at least 1 hour or overnight for best results.

2. Preheat the Oven: Preheat your oven to 375°F (190°C).

3. Dredge the Chicken: Remove the chicken from the marinade and let any excess drip off. Dredge each piece in the all-purpose flour, shaking off the excess flour.

4. Brown the Chicken: In a large skillet over medium-high heat, melt 2 tablespoons of butter. Add the chicken thighs, skin-side down, and cook for about 5-6 minutes until golden brown. Flip and cook for another 5 minutes. Remove the chicken and set aside.

5. Sauté Onions: In the same skillet, add the remaining butter and sauté the diced onion until translucent, about 3-4 minutes.

6. Make the Gravy: Gradually pour in the chicken broth, scraping up any browned bits from the pan. Stir in the heavy cream, thyme, and rosemary. Bring to a simmer.

7. Combine: Return the chicken to the skillet, spooning some of the sauce over each piece. Reduce the heat to low, cover, and let it simmer for about 25-30 minutes, until the chicken is cooked through.

8. Serve: Once cooked, remove from heat and let it rest for a few minutes. Taste the gravy and add salt and pepper if necessary.

9. Garnish: Before serving, sprinkle freshly chopped parsley over the chicken and sauce.

10. Enjoy: Serve the Thanksgiving Smothered Chicken warm, alongside your favorite sides.