Like what? Potatoes? There are a few high calorie-per-area staples that we know how to grow, process, prepare and store at scale. Sure there might be a 'revolution' (like when electricity was discovered), but there are no obvious candidates to what you're saying, nor a real incremental progress path to follow.

And 'easy to grow' is rather dismissive of the vast amounts of progress we've had to make to come to the point we are now...