If you take away their food after the allotted time, they will learn to eat faster! You could also try enforcing no talking during breakfast; if this seems harsh, you could let them listen to music or an audio book while they eat.
I think that anything you can pick up to eat is faster than fork or spoon food, and easier to bring with you if not finished. So toast (peanut butter makes it more filling), muffins, breads, granola bars, bananas, breakfast sandwiches. You can make scrambled eggs in muffin cups in the oven, then each one is a little hand-held food, or you can sandwich it. The yogurt that comes in a pouch or a tube.