You can make these ahead (up to a day); assemble and refrigerate before baking, adding a minute or two bake time. Switch up fillings with other cheeses, deli meats, or sautéed veggies. For a spicy twist, sprinkle red pepper flakes inside with the cheese. Store leftovers in an airtight container up to 4 days, or freeze individually for up to 2 months; reheat in the oven for best texture.