The warmth and ease of a casserole on a cold night meets the subtle and classic flavors of French onion soup in this baked pasta dish. First, you'll brown and caramelize the onions and mushrooms, then mix them together 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.
Cut mushrooms into ¼" slices.
Halve and peel onion. Slice halves into thin strips.
Lightly crush croutons into coarse crumbs.
Cook the Mushroom-Onion Mixture
Heat a large non-stick pan over medium-high heat.
Add 1 Tbsp. olive oil, mushrooms, onions, garlic, ½ tsp. salt, and ¼ tsp. pepper to hot pan.
Cook, stirring occasionally, until onions and mushrooms are caramelized and deep brown, 10-12 minutes.
While vegetables cook, cook pasta.
Cook the Pasta
Once water is boiling, add pasta and cook until al dente, 9-11 minutes.
Drain pasta in a colander, shaking to remove as much water as possible. Reserve pot; no need to wipe clean.
Make the Pasta Mixture
Return pot used to cook pasta to medium-high heat.
Add cream, vegetable base, half the thyme (reserve remaining for garnish), half the cheese (reserve remaining for topping), cooked pasta, and mushroom-onion mixture to hot pot and cook, stirring occasionally, until slightly thickened, 2-4 minutes.
Bake the Casserole
Pour pasta mixture into prepared casserole dish and top with croutons and remaining cheese.
Bake until cheese is golden brown, 10-14 minutes.
Plate dish as pictured on front of card, with remaining thyme. Bon appetit!