The warmth and ease of a casserole meets the subtle and classic flavors of French onion soup in this baked pasta dish. First, you'll caramelize the onions and brown the mushrooms, then mix them with pasta, cream, and thyme, layering flavor upon flavor. Finally, you'll top the casserole with croutons and cheese (just like the soup!) and bake. Richly cheesy and perfectly indulgent, this dish might even top the classic it was inspired by. Tip: Easy way to remove thyme from stem: just pinch the top and run your fingers down the stem. Presto! The leaves should just fall off.