To make this broccoli chicken casserole, you’ll need pasta, broccoli, cooked chicken, mushrooms, cheddar, and a quick from-scratch sauce.
That’s it — no canned soup, no complicated extras.
Chances are, you already have most of what you need in your kitchen.
Simple ingredients, layered together in the best way.
It has that creamy, cheesy, straight-from-the-oven comfort you expect from a classic casserole.
But it tastes fresher, lighter, and more balanced.
Tender broccoli, savory mushrooms, sharp cheddar, and juicy chicken bake together into something cozy and satisfying.
The kind of dinner that feels nostalgic — in the best way.
And the best part? It’s easy.
Boil the pasta, stir together the sauce, bake until golden and melty, and dinner is done.
For Broccoli Chicken Casserole
- Pasta – Use any variety you like. Whole-wheat, traditional, or gluten-free all work well as the base of this bake.
- Broccoli – Fresh florets add texture and color. You can also use thawed frozen broccoli if that’s what you have on hand.
- Cooked Chicken – Diced or shredded chicken keeps this casserole hearty and filling. Rotisserie chicken works perfectly here.
- Onion – Adds a subtle savory sweetness that builds the flavor of the sauce.
- Baby Bella (Cremini) Mushrooms – Bring depth and a rich, earthy flavor to balance the creamy cheese.
- Garlic – Essential for boosting the overall flavor of the dish.
- Butter or Olive Oil – Used to sauté the vegetables and start the sauce.
For the Creamy Cheddar Sauce
- Flour – Helps thicken the sauce so it coats the pasta beautifully.
- Chicken or Vegetable Stock – Adds savory depth while keeping the sauce from feeling too heavy.
- Milk – Creates the creamy base of the sauce.
- Dijon Mustard – A small amount adds subtle tang and enhances the cheese flavor.
- Fine Sea Salt – Balances and sharpens all the flavors.
- Black Pepper – Adds a gentle warmth.
- Sharp Cheddar Cheese – The star of the sauce. Sharp cheddar gives bold flavor and melts beautifully throughout the casserole.
Lightened-Up Broccoli Chicken Pasta Bake
Notes
Ingredients
- 8 ounces uncooked pasta* (I used whole-wheat rotini)
- 1 large head of broccoli*, cut into bite-sized florets (about 1 pound of florets)
- 2 tablespoons butter or olive oil
- 1 small white onion, thinly sliced
- 8 ounces baby bella (cremini) mushrooms, thinly sliced
- 4 cloves garlic, minced
- 3 tablespoons flour
- 1 cup chicken or vegetable stock
- 1 1/2 cups milk
- 1 teaspoon Dijon mustard
- 1/2 teaspoon fine sea salt
- 1/4 teaspoon freshly-cracked black pepper
- 2 cups (8 ounces) shredded sharp cheddar cheese, divided
- 2 cups diced (or shredded) cooked chicken
Instructions
- Preheat the oven to 400°F.
- Cook the pasta. Bring a large pot of well-salted water to a boil and cook the pasta until al dente. About 1 minute before it finishes cooking, stir the broccoli florets into the same pot. Drain the pasta and broccoli together, then set aside.
- Sauté the vegetables. In a large sauté pan over medium-high heat, melt the butter (or warm the oil). Add the sliced onion and cook for 3 minutes, stirring occasionally. Stir in the mushrooms and garlic, and continue cooking for 5 minutes, stirring occasionally, until the mushrooms are tender.
- Build the sauce. Evenly sprinkle the flour over the vegetable mixture and stir to coat. Cook for 1 minute, stirring occasionally. Pour in the stock and stir until most lumps dissolve. Add the milk, Dijon mustard, salt, and pepper, stirring to combine. Continue cooking until the sauce reaches a simmer. Remove from heat and mix in 1 cup of the shredded cheddar until smooth. Taste and adjust seasoning with more salt and pepper if needed.
- Assemble the casserole. In a 9 x 13-inch baking dish, combine the cooked pasta, broccoli, mushroom sauce, and chicken. Toss until evenly coated, then spread into an even layer.
- Bake. Place the dish in the oven, uncovered, and bake for 15 minutes. Remove from the oven, sprinkle the remaining cheddar evenly over the top, and return to bake for 10 more minutes, or until the cheese is fully melted.
- Serve. Enjoy warm, topped with extra black pepper or fresh herbs if desired.
- Pasta: Any variety works well — traditional semolina, whole-wheat, egg-based, gluten-free, or alternative-grain pasta.
- Broccoli: If preferred, substitute 1 pound of frozen broccoli florets (thawed) for fresh broccoli.
1. Can I use frozen broccoli?
Yes! Frozen broccoli works great. Just thaw it first and drain off any excess moisture so your casserole doesn’t turn watery. I use frozen all the time when I need a shortcut.
2. What’s the best chicken to use?
Any cooked chicken will work. Rotisserie chicken is my favorite because it’s easy and flavorful. You can also use baked, poached, or leftover chicken breasts or thighs — just dice or shred before adding.
3. Can I make this ahead of time?
Absolutely. You can assemble the casserole, cover it, and refrigerate for up to 24 hours before baking. When ready to cook, let it sit at room temperature for about 20–30 minutes, then bake as directed.
4. Can I substitute the pasta?
Yes! Regular pasta, whole wheat, gluten-free, or even chickpea pasta will all work. Just cook it to al dente since it will continue cooking in the oven.
5. How do I know when it’s done?
The casserole should be hot and bubbly around the edges, and the cheese on top fully melted. If you like a little golden color, you can broil it for 1–2 minutes at the end — just keep an eye on it so it doesn’t burn.
