One of the secrets to this recipe is the breadcrumbs. Plain, white, fine breadcrumbs work best. We have the best success making our own. Start with a full loaf of sliced, white, gluten-free sandwich bread. Cut off the brown crusts, leaving only the white interior of the slices. Tear the slices into smaller pieces and spread in an even, thin layer on a baking sheet. Bake in the oven at low temperature (150–200 degrees F) until very dry. You only want to dry out the bread, not toast it. Add the dried bread pieces to a food processor and pulse until you have fine, white breadcrumbs.