Pat your chicken pieces completely dry with paper towels. Combine garlic powder, thyme, paprika, salt, and pepper in a small bowl. Season chicken generously on all sides and let rest at room temperature if time allows.

Heat olive oil or butter in a large skillet over medium-high heat until shimmering. Place chicken skin-side down in the hot pan and cook undisturbed for 5-6 minutes until the skin is golden brown. Turn and brown the other side for 2-3 minutes.

Remove the chicken from the pan and set aside. Add diced onions to the pan, sautéing in chicken drippings for 3-4 minutes until translucent. Add minced garlic, followed by carrots and celery, cooking for another few minutes.

Return the chicken to the pan, nestling it among the aromatics. Add 1/4 cup of chicken broth, cover, and reduce heat to medium-low. Cook the chicken until the internal temperature reaches 165°F (74°C).

Remove the chicken from the pan and tent it with foil. To the drippings, add 3 tablespoons of butter if necessary, then sprinkle the flour and stir to create a roux, cooking for 2-3 minutes.

Gradually whisk in chicken broth, simmering for 5-7 minutes until the gravy thickens. Add sage and pepper.

Slowly whisk in heavy cream or milk and adjust seasonings before returning the chicken to the gravy for a few minutes to heat through.