R.J.
Milk really is a super food (proteins, fats, sugars, vitamins & minerals), so if she's downing a big sippy of warm whole milk or hot chocolate (made with milk) in the morning I wouldn't be too concerned. You can add things to it, like instant breakfast or protein powder. But whole milk will get her through.
We often did/do breakfast in the car. One of my son's favorites was scrambled eggs. To make that work with rushed mornings I would scramble them the night before and put them in the fridge in a ziplock twist & seal carrier. Then in the morning I'd zap them warm, and he'd eat them with his fingers in the car. Babywipes for hands when done, and voila.
I mention the eggs... because he always seemed to need to 'work himself up' to cold or crunchy foods in the morning... and we plain and simple didn't have the time.