Pancakes might work. The batter whips up fast and they cook in no time so it will give them time to eat. They can also customize their pancake by dropping different items on top of the uncooked side before it's flipped: (chocolate chips, blueberries, banana slices, strawberries etc.)
Also, waffles in a waffle iron but depending on the # of kids, you may need quite a few going.
Any kind of cookie would be good because most bake in 10-12 minutes and you can have several baking sheets in the oven.