In a small bowl, mix together the garlic powder, onion powder, paprika, thyme, sea salt and black pepper.
Rub the seasoning mixture onto all sides of the chicken legs.
Heat the butter in a large oven-safe skillet over medium-high heat. Place the chicken legs in the skillet and cook for 5 minutes per side, or until golden brown.
Remove the chicken legs from the skillet and set aside on a plate.
Add the garlic and onion to the skillet and sauté for 1-2 minutes, or until the onion is translucent.
Add the mushrooms and cook for 3-4 minutes, or until the mushrooms are golden brown.
Add the white wine and chicken stock and bring to a simmer. Simmer for 5 minutes.
Stir in the heavy cream and return the chicken legs to the skillet.
Transfer the skillet to the preheated oven and bake for 20-25 minutes, or until the chicken is cooked through.