French Onion Chicken Casserole

Casseroles are just the type of dish to make on a cool rainy day, as the smell of the meal baking wafts through the kitchen, making it feel cozy and wonderful. Our French onion chicken casserole is a little unique in the world of one-dish wonders, as it uses French onion dip as one of the base ingredients for the sauce, along with a cream of chicken soup. Dijon mustard adds a little kick and more flavor in a decidedly French way. And since this recipe uses chicken that’s already cooked, the casserole bakes in about 30 minutes. It’s warm, it’s wonderful and it’s incredibly easy to make.

Ingredients for French Onion Chicken Casserole

• Unsalted condensed cream of chicken soup: Using the unsalted variety keeps the sodium much lower than the standard soup of the same variety. Use this canned condensed soup without diluting it first.
• French onion dip: The dip adds a bit of a tangy, creamy flavor, as well as small bits of onions. Use store-bought or make your own caramelized onion dip for a homemade touch.
• Dijon mustard: Dijon mustard adds flavor depth; it also pairs well with chicken, as in this chicken Dijon recipe.
• Sherry (optional): The sherry adds a hint of sweetness to the dish. The alcohol cooks away, so there’s no need for concern about the alcohol content.
• Cooked chicken breast: Cut the chicken into bite-sized cubes for this recipe.
• Cheddar cheese: Shredded cheddar cheese makes a lovely tangy topping for the casserole. Grate your own off a block of cheddar to get more value for the money, for fresher taste and to avoid the preservatives added to packaged shredded cheese to make it last longer.
• Fresh thyme: As a member of the mint family, thyme adds a hint of flavor that’s both sweet and savory. Mincing the thyme releases its fragrant oils.
• French-fried onions: Canned French-fried onion adds a lot of crunch and flavor as a casserole topping.

Directions 

Step 1: Mix the ingredients

Preheat the oven to 350°F. In a large bowl, combine the soup, dip, mustard and, if desired, sherry, stirring until the mixture is smooth. Stir in the chicken, 1/2 cup of the shredded cheddar cheese and the thyme.

Step 1: Bake the casserole

Transfer the mixture to a greased 2-quart baking dish. Sprinkle the casserole with the remaining 1/2-cup of cheddar cheese and the French-fried onions. Bake the casserole, uncovered, until it’s heated through, or about 25 to 30 minutes. Allow the casserole to rest for a couple of minutes before digging in.

Recipe Variations

• Add mushrooms: Add sliced mushrooms or canned mushroom stems and pieces, drained, for mushroom flavor and texture in this French onion soup chicken casserole.
• Add garlic: Add a few cloves of minced garlic or a tablespoon or so of powdered garlic to add umami and a little garlic flavor to the casserole.
• Swap cheeses: Instead of solely using cheddar cheese inside and atop the casserole, mix things up and replace half of the cheddar with Swiss, gruyere or provolone. A sprinkle of another cheese such as Parmesan or smoked gouda on top changes the flavor profile, too.

How to Store French Onion Chicken Casserole

When the casserole is completely cool, transfer the leftovers to an airtight container and store it in the refrigerator. It will keep for 3 to 4 days.

Can you make French onion chicken casserole ahead of time? 

Sure! Prepare all the ingredients as directed and place them in the casserole, except for the French-fried onions, as they may get soggy. Cover the dish and store it in the refrigerator. When you’re starting to get hungry, add the French-fried onions and pop the casserole in the oven, following the baking directions.

French Onion Chicken Casserole Tips

Could I use rotisserie chicken for this casserole?

Sure! Cut the chicken into small bites, or even shred it a bit. A casserole is an excellent way to use up chicken leftovers.

Should I use sherry or cooking sherry?

Either type will work for this recipe; the main difference is that cooking sherry has added preservatives and salt. If you have both types of sherry, the sherry meant for drinking is the better choice, as it won’t add sodium.

Could I use mushroom soup instead?

Yes; a no-salt-added condensed cream of mushroom is just as tasty and works famously well in casseroles. In a pinch, a condensed cream of celery soup would even work.