Make-ahead tip: The bake could be prepared a day ahead. Cool; cover and refrigerate overnight. Remove from refrigerator 40 minutes before baking. Bake dish as directed.
Flecked with chopped chilies, pepper jack is a blend of mild monterey jack cheese with, typically, green and red jalapeño peppers. The peppers give the cheese a spicy kick, and the level of heat varies by the brand.