Place each chicken breast between two pieces of plastic wrap (or inside a large ziploc bag) and pound with a heavy object (ie a rolling pin, wine bottle, or heavy salt container) until they are about ¼ inch in thick. This is fun and an excellent way to get out some pent up aggression.
In a small bowl combine lemon juice, olive oil, shallot, garlic, and chili flakes. Mix well. Pour the marinade into a quart sized ziploc bag and add the pounded chicken breasts. Make sure all the breasts are evenly coated. Refrigerate for 15 minutes (or more, if you have the time/patience) to marinate the chicken.
Heat a grill pan (don’t worry, you can also use a regular pan). Remove chicken from the marinade and sprinkle both sides of the breasts with salt and fresh ground pepper. Cook the chicken for about two minutes on each side. Serve hot or cold.