Although it might sound unusual, lettuce is a fresh addition that will brighten up any number of casseroles, bakes, or hot dishes. Along with providing extra nutrients and fiber, crisp and crunchy lettuce varieties can also add another textural element to contrast typically smooth and creamy fillings. What's more, lettuce also amps up flavor by offering a fresh and vegetal brightness that cuts through the rich and savory qualities of a casserole. If that weren't enough, leafy greens can even add an unexpected aesthetic value.