Heat the broth in a small pot until almost simmering. Peel the onion and garlic; dice the onion and mince the garlic. Heat the oil in a large skillet or shallow pot over medium-high heat. Add the chicken breasts to the hot oil and cook them on both sides until lightly browned then remove them to a plate. To the same hot oil add the onion and garlic and saute it for a minute or two. Add the saffron and stir it in the oil for a few seconds then add the rice. Stir the rice to coat it with the oil and saffron, then pour in the hot broth. Add a pinch or two of salt and pepper. Bring the broth to a boil, then lower it to a simmer. Add the chicken breasts to the simmering broth and cover the pan with a lid or foil. Cook the chicken and rice for eighteen minutes then remove it from the heat and allow it to rest for five minutes.