Preheat the oven to 375°F. In a bowl, mix the olive oil, thyme, tarragon, oregano, garlic powder, lemon juice, salt, and pepper.
Add the chicken to the bowl and coat with the herb mix.
Place the chicken breasts in a baking dish with the rosemary. Place the dish in the oven and bake for 20 minutes.
Take the baking dish out of the oven. Place the butter on the chicken and let it melt. Let the chicken rest for 5 minutes before serving.