Chicken Broccoli Casserole

Some meals feel like they’ve been part of your life forever. Not because they’re flashy or trendy, but because they work—on busy nights, on slower ones, when you need to feed people well and make it count.

This chicken broccoli casserole is exactly that. It’s rich where it should be, crisp where it matters, and full of flavor from edge to edge.

There’s a clean kind of satisfaction in layering it all together—the creamy base, tender chicken, roasted broccoli, sharp cheddar melting into every corner, and those golden croutons that give it just enough crunch to keep things interesting.

Nothing thrown in just to fill space. Everything has a reason to be there.

You’ll know it’s ready when the edges start to bubble and the cheese turns that deep amber around the sides. It smells like home.

It looks honest. It tastes like effort without the show. This isn’t a shortcut meal—it’s real food that holds its own.

Chicken Broccoli Casserole Recipe

Ingredients

3 cups cooked chicken breast, diced (tender but firm)
3 cups broccoli florets (steamed until just fork-tender)
2 cups shredded sharp cheddar cheese (freshly grated for best melt)
1 ½ cups sour cream
½ cup mayonnaise
1 tablespoon Dijon mustard
1 teaspoon garlic powder
½ teaspoon onion powder
¼ teaspoon ground black pepper
¼ teaspoon salt (adjust to taste)
1 teaspoon lemon juice (optional, for brightness)
1 cup seasoned croutons (buttery, store-bought or homemade)
¼ cup grated mozzarella (for subtle creamy pull, optional)
1 teaspoon olive oil or melted butter (to toss the croutons if homemade)

Instructions

Preheat your oven to 375°F (190°C) and lightly grease a 9×13-inch casserole dish with cooking spray or a thin brush of olive oil.

In a large mixing bowl, combine sour cream, mayonnaise, Dijon mustard, garlic powder, onion powder, salt, black pepper, and lemon juice (if using). Whisk until completely smooth.
Gently fold in the diced cooked chicken and steamed broccoli. Mix until everything is evenly coated in the creamy base.
Pour the mixture into the prepared casserole dish and spread it out evenly using a spatula or the back of a spoon.

Sprinkle the sharp cheddar cheese evenly over the top. If using mozzarella, add it now for extra meltiness beneath the cheddar.
Scatter the seasoned croutons evenly across the top. If using plain or homemade croutons, toss them first in a teaspoon of olive oil or melted butter for a golden crunch.
Place the casserole uncovered in the center rack of your preheated oven.

Bake for 25–28 minutes or until the edges are bubbling and the cheese is fully melted and beginning to brown slightly.
For a crispier topping, switch to broil during the last 2 minutes, but watch closely to avoid burning the croutons.
Let the casserole rest for 5–7 minutes before serving — this helps the layers settle and enhances flavor cohesion.

Can I Use Frozen Broccoli Instead Of Fresh?

Yes, frozen broccoli can be used, but it needs a little preparation to get the texture and taste just right.

Frozen broccoli is often picked and frozen at its peak, so it still holds nutrients.

However, using it straight from the freezer will make your casserole watery and mushy. To get the best results, follow these steps:

Thaw Completely: Before mixing it into the casserole, let the broccoli thaw fully. You can do this by leaving it in the fridge overnight or placing it in a bowl of cold water for faster thawing.
Drain Excess Water: After thawing, pat the broccoli dry with paper towels. Press lightly to remove trapped moisture, which can make the creamy base runny.
Chop Large Pieces: Sometimes frozen broccoli comes in bigger chunks. Cut them into smaller florets for even distribution in the casserole.

Pre-Cook If Needed: If the broccoli still feels firm or icy, steam or microwave it for a minute or two until just tender.

Fresh broccoli gives you more control over texture, but properly handled frozen broccoli is a great substitute that still gives you that bright color and soft bite.

What Type Of Chicken Should I Use?

Choosing the right chicken makes a big difference in the flavor and texture of the casserole.

This dish works well with various types of cooked chicken, and here’s how to decide what fits your time, budget, or what you already have:

Cooked Chicken Breast: This is the most common choice. It’s lean, easy to dice, and absorbs flavors from the creamy sauce.
Leftover Chicken: If you’ve roasted or grilled chicken from another meal, chop it up and use it here. Just avoid overly spiced or sauced leftovers.

Rotisserie Chicken: Store-bought rotisserie chicken adds flavor and saves time. Be sure to remove the skin and bones before mixing it in.
Poached Chicken: This method gives tender, juicy chicken with a very neutral taste that blends smoothly into the casserole.
Shredded Chicken Thighs: If you prefer dark meat, chicken thighs add extra flavor and stay moist after baking.

Can I Make Chicken Broccoli Casserole Ahead Of Time?

Yes, this casserole is perfect for prepping in advance—ideal for busy weekdays, meal plans, or when hosting.

You can prepare it completely, right up to the baking step, and then store it in the fridge. Here’s how:

Assemble In Advance: Mix all ingredients and layer the casserole as if you were about to bake it. Don’t add the croutons yet—they’re best added just before baking to keep them crisp.

Cover Tightly: Use plastic wrap or a tight lid to seal the dish and store in the fridge for up to 24 hours before baking.
Add Extra Bake Time: If you’re putting it into the oven straight from the fridge, add an extra 5–10 minutes to the baking time to heat it evenly.
For Longer Storage: You can also freeze the unbaked casserole (again, without croutons on top). Wrap well with foil and freeze for up to 2 months. Let it thaw in the fridge overnight before baking.

How Do I Store Leftover Chicken Broccoli Casserole And Reheat It?

This casserole holds up really well after baking, and storing it properly means you’ll enjoy it just as much the next day.

Cool Before Storing: Let the casserole cool down to room temperature before covering or transferring it to containers.
Refrigerator Storage: Store leftovers in an airtight container or cover the baking dish tightly. It will stay fresh in the fridge for up to 3 days.

Freezing Leftovers: Yes, you can freeze it. Portion it into freezer-safe containers and freeze for up to 1 month. Keep in mind the texture may soften slightly, especially the croutons.
Reheating In The Oven: Place a portion in an oven-safe dish, cover loosely with foil, and bake at 350°F (175°C) for about 15–20 minutes until hot.
Reheating In The Microwave: Place a single serving on a microwave-safe plate, cover lightly with a paper towel, and heat in 30-second bursts until warm. Microwaving is faster but won’t keep the croutons crispy.

What Can I Use Instead Of Croutons?

If you don’t have croutons, or simply want to switch things up, there are several tasty options to keep the crunchy topping.

The crispy layer adds texture and balance to the creamy filling, so it’s worth finding a good substitute:

Toasted Breadcrumbs: Lightly toast seasoned breadcrumbs in a pan with a little butter or olive oil. Spread over the top before baking.

Crushed Crackers: Use buttery crackers like saltines or round snack crackers. Crush them up and sprinkle over the casserole for a golden crust.
Toasted Panko: Panko breadcrumbs are extra crispy. Mix them with melted butter and toast lightly before adding.
Toasted Flatbread or Pita Chips: Break up plain pita chips or toasted flatbread into small pieces for a unique, crunchy finish.