A savory and rich bread stuffing with all the flavors of classic stuffed mushrooms. This casserole features a base of day-old bread cubes mixed with browned Italian sausage, sautéed mushrooms, bell peppers, and scallions, all bound together with broth, Parmesan, and eggs. The dish is uniquely topped with large mushroom caps that are themselves filled with a portion of the stuffing, coated in a crispy panko-Parmesan crust, and then baked along with the rest of the casserole until golden brown.