•This recipe may be baked in any 2-quart casserole. I like the 9-inch square pan because it provides a good ratio of crispy surface area to gooey inside. If you use a 9-inch round casserole, which will yield slightly less surface area, you may want to use about 3/4 of the topping recipe.
•Crushed Rice Chex is my go-to substitute for panko and breadcrumbs when cooking gluten-free. In fact, I like the taste and texture enough to use them even when cooking for those who eat gluten. I crush a large quantity and store in an airtight container to have on hand as needed. A zipper-top bag (or the sturdy cereal bag in which they come) and a rolling pin make quick work of this-as does a food processor. Take care to crush them evenly yet not to the point of sand.