1. Rinse chicken breasts and pat dry with paper towels.
2. Season with salt, pepper, garlic powder and thyme on both sides.
3. Preheat oven to 350F (180C).
4. Heat olive oil in a cast iron skillet over medium-high heat.
5. Saute chicken for 3 minutes on each side, to form a nice crust.
6. Transfer skillet to the preheated oven and bake chicken for another 8 minutes, or until done.
7. Meanwhile, cut sage leaves into thin strips.
8. Transfer chicken to a plate and cover with foil (to keep it warm).
9. Put the same skillet over medium-low heat. Scrape any brown bits from the bottom, add butter (or ghee), chopped sage and cook stirring for 1 minute.
10. Pour over chicken and serve.