Best straight from the oven. Leftovers keep 2 days and reheat well in a dry skillet or air fryer at 350°F for 5 minutes; the microwave makes the base leathery.
Too much sauce, or a cold baking surface. Preheat the tray, and spread the sauce thin enough to see the bread through it.
Not on a 10-minute bake — it won't cook through safely. Cook and shred it first, which is why the recipe assumes cooked chicken.
Something on the tangier side. Very sweet sauces burn at 450°F and can taste cloying against the cheese.