Place chicken between 2 sheets of plastic wrap and pound lightly with a mallet or other heavy flat object to flatten slightly. Season with salt and pepper to taste.
Heat oil in a heavy nonstick pan over medium high heat. Add rosemary and crushed garlic. Sauté 1-2 minutes, pressing down on rosemary and garlic to release flavor. Remove with a slotted spoon and discard.
Sauté chicken 5 minutes per side, turning frequently until browned and cooked throughout. Stir in minced garlic during last 2 minutes of cooking.