To construct this Overnight Croissant Breakfast Casserole gluten-free while still holding its satisfying flavors you can make a few substitutions. Rather than using butter croissants use your selected gluten-free bread or pastry that has a similarly rich and buttery taste to preserve the dish's indulgent texture. As, for the gravy select a gluten-free all-purpose flour blend that thickens smoothly and evenly without forming lumps so your sauce turns out just, as creamy and delightful.