4-Ingredient Chicken Alfredo Pasta Bake

Preheat the oven to 400°F.

Bring a large pot of water to a rolling boil over high heat. Season the pasta water with the salt, then add in the penne. Give the pasta a good stir to ensure it isn't sticking together. Cook for 3 minutes, then add the broccoli and stir again. Cook until the penne is very al dente and the broccoli is tender, about 4 minutes more. Reserve about 1 cup of the starchy cooking water before draining the pasta and broccoli in a colander in the sink.

Pour the cooked penne and broccoli back into the large pot. Add the shredded chicken, Alfredo sauce, and reserved pasta water and mix thoroughly. Pour the contents into a 9x13-inch casserole dish or baking pan and smooth into an even layer with a spoon or spatula.

Transfer the casserole to the oven and bake until the top layer has started to brown, about 20 minutes.

Let the casserole cool at room temperature for 15 minutes before serving.