We found that there was something about pizza cheese that was harder to tolerate than other milk products. We dropped the pizza and went back to baked milk. My son was up to a quarter cup of milk and 2 Tbsps butter before we stopped for the trial.
He was just never able to tolerate the pizza cheese, even when we baked it to the point of inedibility.
My guess? Skim mozzarella is higher in protein load than almost any other type of cheese.
Lasagna and 'cheese sticks' would probably be equally hard to handle, as are 'low-fat' milk sources. For whatever reason, concentration seems, at least in some kids, to be just as important as denaturation or overall dose.
RE: microwaving-- even with a good microwave and turntable-- inevitably leaves some areas less 'cooked' than others, and may not get food hot enough (effective temps of only 220-275F aren't uncommon).
(Yes, this is one of those things that we learned in our DIY updosing with milk over the past seven years.)
I second what someone else already mentioned, too, which is that Dairy is one of those things that, even seven years later, we're
still having to tweak based on day-to-day threshold. In otherwords, it moves around about as much as the NASDAQ. <sigh>