Once boiling, add pasta and cook until al dente, 9-11 minutes.
Reserve ½ cup pasta cooking water. Drain pasta in a colander. Set aside.
While pasta cooks, prepare ingredients.
Prepare the Ingredients
Halve and peel onion. Slice halves into thin strips.
Cut mushrooms into ¼" slices.
Crush croutons into coarse crumbs.
Pat chicken breasts dry and, on a separate cutting board, cut into 1" pieces. Season with ¼ tsp. salt and a pinch of pepper.
Sear Chicken and Cook Vegatables
Place a large non-stick pan over medium-high heat and add 1 tsp. olive oil.
Add chicken to hot pan and cook undisturbed until browned, 2-3 minutes.
Then, stir occasionally until browned on two sides, 2-3 minutes.
Transfer chicken to a plate. Chicken will finish cooking in a later step.
Keep pan over medium-high heat and add 2 tsp. olive oil.
Add onions, mushrooms, and garlic to hot pan and stir occasionally until caramelized, 6-8 minutes.
Season with ¼ tsp. salt and a pinch of pepper.
Make the Sauce
Add cream, chicken demi, reserved pasta water, and chicken and any accumulated juices. Stir constantly until thick enough to coat the back of a spoon, 3-5 minutes.
Remove from burner and stir in pasta.
Bake the Pasta
Place prepared casserole dish on prepared baking sheet to catch any drips. Transfer pasta to casserole dish. Top with breadcrumbs , then mozzarella.
Bake in hot oven until cheese is melted, 6-8 minutes.
Plate dish as pictured on front of card. Bon appétit!