I hope the question isn't too vague. I'm particularly interested in learning more about it's formation and how it's power developed in it's early stages. Any feedback would be appreciated!
If you're talking about the origins of the Carolingian Empire, there's a ton of good books. If you're interested in scholarly history, The Frankish Kingdoms under the Carolingians by Rosamond Mckitterick is a good one.
However if you're talking about the origins of the Ottonian dynasty Holy Roman Empire and onward, I believe one of the few books for that era is Germany in the Early Middle Ages by Timothy Reuter.
For a more general look at both, I have a copy of the Oxford History of Medieval Europe, which covers the background and the life of both, although because it's more of a general overview, a lot of details are missing, but perhaps that's best, given the rabbit hole of history that is the Holy Roman Empire.