Description

Sometimes, nothing beats a warm, cheesy casserole that you can dig into after a long day. And when it’s a dish like Chicken Alfredo Casserole, it feels like you’re wrapping yourself in a cozy blanket of flavors. Tender chicken, perfectly cooked pasta, a rich and creamy Alfredo sauce, and melty cheese combine in this casserole to create a comforting meal that’s both satisfying and easy to prepare.

This casserole is the type of dish that brings families together. It’s versatile, forgiving, and doesn’t require hours of prep work or complicated ingredients. Whether you’re making it for a weeknight dinner or preparing a meal to bring to a gathering, this chicken Alfredo casserole will undoubtedly earn its spot in your regular recipe rotation.

Ingredients

Scale

3 boneless, skinless chicken breasts – You can also use thighs if you prefer darker meat or even shredded rotisserie chicken for an even quicker option.
1 small red onion, chopped – This adds a bit of sweetness and depth to the dish, perfectly complementing the rich Alfredo sauce.
3 garlic cloves, minced – Garlic is a must in any dish that involves cream; it adds an aromatic punch and enhances the overall flavor.
1 (16-ounce) package penne pasta – Penne works beautifully for this casserole because it’s great at holding onto the sauce, but feel free to use any short pasta like ziti or rigatoni.
1 (15-ounce) jar Alfredo sauce – You can use store-bought or homemade. If you prefer a homemade sauce, simply make it by combining butter, heavy cream, and Parmesan.
1 1/2 cups shredded mozzarella cheese, divided – Mozzarella offers that classic gooey, melty texture we all crave in casseroles.
1/4 cup milk – Just a little bit to help loosen up the sauce and make it even creamier.
1 cup shredded Cheddar cheese – The sharpness of cheddar contrasts wonderfully with the mild mozzarella and adds an extra layer of flavor.

Instructions

Preheat the Oven: Start by preheating your oven to 350°F (175°C). This gives the oven time to get hot while you prepare the casserole, ensuring everything cooks evenly and quickly once it’s in there.
Cook the Chicken: In a large skillet, heat a tablespoon of oil or butter over medium heat. Add the chicken breasts, seasoning them lightly with salt and pepper, and cook them for 5-7 minutes per side until golden brown and cooked through. You want the chicken to be fully cooked but not overdone—aim for an internal temperature of 165°F (74°C).
Add the Onion and Garlic: When the chicken is cooked through, remove it from the skillet and set it aside. In the same pan, add the chopped red onion and minced garlic. Sauté them together for 2-3 minutes until fragrant and the onions have softened. This will add even more flavor to the casserole and help deglaze the pan, picking up any bits of golden chicken that add extra depth.
Cook the Pasta: While the chicken is cooking, bring a large pot of salted water to a boil. Add the penne pasta and cook according to the package directions (usually about 10-11 minutes). Drain the pasta once it’s tender but be sure to leave it slightly undercooked since it will continue cooking in the oven.
Shred the Chicken: Once the chicken has cooled for a few minutes, cut it into bite-sized pieces or shred it with two forks. This will allow it to distribute evenly throughout the casserole.
Mix Everything Together: In a large mixing bowl, combine the cooked chicken, sautéed onions and garlic, pasta, Alfredo sauce, 1 cup of mozzarella cheese, and milk. Stir everything together gently until the mixture is well combined.
Assemble the Casserole: Pour the entire mixture into a 1 1/2-quart casserole dish, spreading it out evenly. Top it off with the remaining mozzarella cheese and the shredded cheddar cheese. The more cheese, the better!
Bake: Place the casserole in the preheated oven and bake for 25 minutes, or until the cheese is melted, bubbly, and golden brown around the edges. Your kitchen will soon be filled with the irresistible aroma of creamy, cheesy goodness.
Let it Rest: Once done, take the casserole out of the oven and let it sit for about 5 minutes. This allows the sauce to thicken and the casserole to set, making it easier to serve.
Serve and Enjoy: Scoop a generous portion of the casserole onto each plate, making sure to get a little bit of chicken, pasta, and cheese in every bite. Enjoy this cozy dish with a side of garlic bread or a simple salad.

Notes

Storing Leftovers: Leftovers can be stored in an airtight container in the refrigerator for up to 3-4 days. The flavors actually improve the next day as they marinate together!
Freezing: While this dish can be frozen, the texture of the Alfredo sauce may change slightly when reheated. To freeze, assemble the casserole without baking, then cover tightly and freeze. When ready to bake, simply thaw in the fridge overnight and bake as directed, adding a few extra minutes if needed.