This recipe has been a weeknight lifesaver and a potluck favorite in my home for years. I first put this combination together on a rainy Thursday evening when the pantry had cooked pasta and leftover chicken and I wanted something that felt indulgent but still used what I had on hand. The result was an ultra creamy, cheesy bake with tender chicken and a golden, bubbling top that keeps everyone coming back for seconds. The texture balances soft pasta, saucy pockets of cheese, and slightly crisped edges from baking.

What makes this casserole special is its flexibility and the comforting familiarity of its flavors. It is simple enough to come together in under 45 minutes if the chicken and pasta are already cooked, yet sophisticated in its use of a light roux and sour cream to create a smooth, clingy sauce. I still remember my neighbor walking in on the aroma and insisting I hand over the recipe. Over time I have learned little tricks to keep the sauce velvety and to prevent the top from drying out while creating that perfect golden finish.

Ingredients

• Cooked chicken 2 cups: Use leftover roasted or poached chicken cut into bite sized pieces. Rotisserie chicken works wonderfully for convenience and a rich flavor. Aim for white meat if you prefer a milder taste.
• Cooked pasta 4 cups: This is about 2 cups uncooked. Use short shapes such as penne, cavatappi, or rigatoni which trap sauce. Cook to just al dente so the pasta does not go mushy during baking.
• Butter 3 tablespoons: For the roux base. Unsalted allows control of seasoning; use salted if that is what you have and cut the added salt slightly.
• Onion 1 small: Finely chopped for sweetness and depth. Yellow onion is classic for casseroles, but sweet onion will mellow the bite.
• Garlic 2 cloves: Minced fresh garlic provides aromatic lift. Avoid pre minced in oil for fresher flavor.
• All purpose flour 2 tablespoons: Thickens the sauce. Measure by spooning into the cup for accuracy or use a digital scale for precision.
• Sour cream 1/2 cup: Adds tang and silkiness. Full fat gives the creamiest result but low fat will still work.
• Milk 1 cup: Whole milk creates a richer sauce. If using 2 percent expect slightly thinner texture and consider an extra tablespoon of flour if needed.
• Cheese 3 cups grated: Choose sharp cheddar, Colby jack, Swiss, or a mix. Reserve 1/2 cup for the top. Freshly grate for best melt and flavor.
• Red pepper flakes 1/2 teaspoon: Brightens the dish with a gentle heat. Omit or reduce for children or spice averse eaters.
• Salt and black pepper: To taste. I start with about 1 teaspoon kosher salt and 1/4 teaspoon black pepper for the whole casserole and adjust before baking.

Instructions

Preheat oven and prepare dish Preheat the oven to 350 degrees Fahrenheit. Lightly grease a 9x13 inch baking dish or spray with nonstick cooking spray to prevent sticking and make cleanup easier. Preheating ensures even baking and a consistent bubbling finish. Sauté aromatics In a large skillet melt 3 tablespoons butter over medium heat. Add the finely chopped onion and minced garlic and sauté until softened and fragrant, about 3 to 4 minutes. Look for translucent edges on the onion and a sweet, savory scent from the garlic without any browning. Make a roux and sauce Stir in 2 tablespoons flour and cook for about 1 minute while stirring. This cooks the raw flour taste away. Slowly whisk in 1 cup milk and then add 1/2 cup sour cream. Continue whisking until the sauce begins to thicken, about 3 to 4 minutes at a gentle simmer. The sauce should coat the back of a spoon. Incorporate cheese and seasonings Remove the pan from heat and stir in 2 1/2 cups of the grated cheese until smooth. Add 1/2 teaspoon red pepper flakes, and salt and black pepper to taste. Keep the heat low to prevent the cheese from becoming grainy. Combine pasta and chicken Add the cooked chicken and 4 cups cooked pasta to the sauce and toss until evenly coated. Ensure pieces of chicken are bite sized so they warm through evenly without drying. Assemble and bake Transfer the mixture to the prepared 9x13 inch baking dish. Sprinkle the reserved 1/2 cup cheese evenly across the top. Bake in the preheated oven for 20 to 30 minutes or until the top is bubbling and golden brown. Let rest for 5 minutes before serving so the sauce sets slightly.

Storage Tips

Store any leftovers in an airtight container in the refrigerator for up to 3 days. For best results, portion into individual containers to reheat single servings more evenly. When reheating, cover the container loosely and heat at 350 degrees Fahrenheit for 15 to 20 minutes until warmed through. If refrigerated sauce has thickened, stir in 1 to 2 tablespoons of milk before reheating to restore creaminess. For freezing, cool completely then wrap the baking dish tightly with plastic wrap and foil or transfer to a freezer safe container for up to 3 months.

Ingredient Substitutions

To make this lighter, substitute Greek yogurt for half the sour cream and use 2 percent milk. For a gluten free version, replace the all purpose flour with a 1 to 1 gluten free flour blend or use cornstarch to thicken the sauce, mixing 1 tablespoon cornstarch with a little cold milk before whisking into the hot liquid. Swap cheeses to change flavor profile: Gruyere or smoked gouda add depth while Monterey jack keeps a milder melt. For a vegetarian variation double the vegetables and use a plant based chicken substitute but note the dairy remains unless substituted.

Serving Suggestions

Serve hot with a crisp green salad dressed lightly in lemon vinaigrette to cut through the richness. A side of steamed green beans or roasted broccoli complements the cheesy texture. For a heartier meal, pair with crusty bread or garlic knots. Garnish with chopped fresh parsley or chives and a light sprinkle of extra red pepper flakes for heat. For potlucks serve directly from the baking dish on a trivet with a serving spoon so guests can help themselves.

Cultural Background

This style of baked pasta and protein casserole is rooted in comfort food traditions across many cultures where combining starch, sauce, and protein into a single dish is a practical and convivial approach to family meals. In American kitchens casseroles became especially popular in the mid 20th century as convenient ways to feed families, often using leftover ingredients. The use of a basic roux and cheese connects to classic French techniques while the baked assembly mirrors traditional gratin approaches in European cooking.

Seasonal Adaptations

Adapt this dish through the year by folding in seasonal vegetables. In spring add asparagus tips and peas. In summer fold in roasted zucchini and cherry tomatoes. In autumn incorporate roasted squash and sage and in winter add spinach or kale and a sprinkle of nutmeg to the sauce for warmth. Each seasonal change alters the flavor while preserving the comforting base of chicken and cheese.

Meal Prep Tips

For efficient meal prep, cook the pasta and chicken the day before and store separately. Prepare the sauce and combine everything in the baking dish, then cover and refrigerate. When ready to serve, simply bake as directed. To convert to single serving meal prep, divide into six 2 cup portions in oven safe containers and refrigerate. Reheat covered at 350 degrees Fahrenheit until hot, checking after 12 to 15 minutes for individual portions.

Making this casserole is an easy way to turn simple ingredients into something memorable. It rewards small attentions like freshly grated cheese and careful seasoning and invites experimentation. Share it at a family dinner and enjoy the easy conversation that comes with a comforting, crowd pleasing dish.