Pat the chicken thighs dry and season them on both sides with salt, pepper, garlic powder, onion powder and paprika. Heat the olive oil in a large skillet over medium high heat. Add the chicken and sear them for about 5 minutes per side, until nicely browned. Remove the chicken from the skillet and set it aside.
Reduce the heat to medium and add the diced onion to the same skillet. Sauté for about 3–4 minutes, stirring occasionally, until the onion begins to soften. Add the butter and let it melt, then sprinkle in the flour. Stir everything together and cook for about 1–2 minutes to remove the raw flour taste.
Slowly pour in the chicken broth while whisking continuously to keep the gravy smooth. Be sure to scrape up all of the browned bits from the bottom of the skillet because they add tons of flavor.
Stir in the heavy cream, parsley, salt, pepper and ½ teaspoon of garlic powder and let the gravy gently simmer for about 2–3 minutes, or until it begins to thicken. Return the chicken thighs and any accumulated juices back to the skillet, nestling them into the gravy.
Reduce the heat to medium-low, cover and simmer for about 8–12 minutes, or until the chicken is cooked through and reaches an internal temperature of 165°F. Spoon the gravy over the chicken, garnish with additional parsley if desired and serve warm.