For a lighter version, you can substitute the heavy cream with half-and-half or milk, though the sauce will be less rich. Try adding different vegetables like peas, spinach, or bell peppers for added texture and nutrition. If you wish to make it gluten-free, use gluten-free pasta and a suitable thickener such as cornstarch instead of all-purpose flour. For an added crunch, consider topping the casserole with breadcrumbs mixed with a bit of melted butter before baking.