High Protein Chicken Casserole (Easy & Creamy)

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This chicken casserole combines rotisserie chicken, rice, and broccoli in a creamy Greek yogurt sauce instead of canned soup, finished with melted cheddar. Each serving provides approximately 28g of protein, depending on the ingredients and brands used.

Why You’ll Like this High Protein Chicken Casserole

The creamy sauce uses Greek yogurt instead of canned cream soup. A quick roux thickens the base, while the yogurt adds creaminess and additional protein, whisked in off the heat so it stays smooth instead of curdling — the same approach used in the sauce for my Greek yogurt chicken pasta.

Using already-cooked rice keeps the casserole simple. Rather than baking raw rice in liquid, the rice is cooked ahead of time, so the oven’s main job is heating the casserole through and melting the cheese.

Rotisserie chicken keeps the prep manageable. Shredding chicken that’s already cooked and seasoned cuts out a full step without sacrificing flavor.

Ingredients

2 cups cooked, shredded chicken (rotisserie works well)
3 cups cooked long-grain white rice
2 cups broccoli florets, steamed or blanched until crisp-tender
2 tbsp butter
2 tbsp all-purpose flour
1 cup milk
¼ cup chicken broth
1 cup plain Greek yogurt
½ tsp garlic powder
½ tsp onion powder
Salt and black pepper, to taste
1 cup shredded cheddar cheese, divided

How to Make High Protein Chicken Casserole

Preheat the oven to 375°F and grease a 9×13-inch baking dish.
In a saucepan over medium heat, melt the butter, then whisk in the flour and cook for about 1 minute. Gradually whisk in the milk and broth, and cook, stirring, until the sauce thickens, about 3 minutes.

Remove the sauce from the heat and let it cool slightly, then whisk in the Greek yogurt until smooth — doing this off the heat keeps it from curdling. Stir in the garlic powder, onion powder, salt, pepper, and half the cheddar.
In a large bowl, combine the cooked rice, chicken, and broccoli. Pour the sauce over and mix until everything is evenly coated.

Transfer the mixture to a 9×13-inch baking dish and top with the remaining cheddar.

Bake uncovered for 20 to 25 minutes, until bubbling and the cheese is melted. Since the chicken and rice are already cooked, this step is about heating everything through evenly — check with an instant-read thermometer that the center reaches 165°F.

Let the casserole rest for 5 minutes before serving.

Substitutions

Rice: brown rice or a different cooked grain can work in place of white rice — since the rice is already cooked before it goes into the casserole, this is a simpler swap than it would be with raw rice, but the texture and flavor will vary by grain.

Dairy: this recipe is written and tested with plain Greek yogurt. Cottage cheese (blended smooth) would likely work as a milder, creamier alternative, following the same off-heat method, but I haven’t tested that version — if you try it, treat it as an experiment rather than a confirmed swap.

Vegetables: frozen broccoli works in place of fresh; thaw and drain it well first so it doesn’t add extra water to the sauce.

Make-Ahead and Storage

I haven’t tested assembling and refrigerating the entire casserole before baking, so I recommend preparing it as written. You can still save time by cooking the rice, chicken, and broccoli ahead and refrigerating them separately until you’re ready to assemble the casserole.

Refrigerate leftovers in an airtight container within 2 hours of cooking, for up to 3 to 4 days. Reheat in a 325°F oven or in the microwave until the center reaches 165°F.

FAQ

Can I use cottage cheese instead of Greek yogurt? I haven’t tested a cottage cheese version of this specific recipe, so I can’t confirm the exact result. If you try it, blend it smooth first and use the same off-heat method described below.

Why whisk in the yogurt off the heat? Adding dairy to a very hot sauce can cause it to curdle or separate. Letting the sauce cool slightly first, then whisking the yogurt in off direct heat, keeps the texture smooth.

Can I use raw chicken instead of rotisserie chicken? Yes, but cook it fully first — either poach or bake it separately, then shred it, since this recipe’s bake time is meant to heat already-cooked ingredients through rather than cook raw chicken from scratch.

Can I use frozen broccoli? Yes. Thaw it and drain off any excess water before adding it, so it doesn’t make the sauce watery.

How do I know the casserole is done? Check with a food thermometer that the center has reached 165°F, and look for the cheese to be melted and the edges bubbling.

Have leftover rotisserie chicken on hand? Check out my leftover rotisserie chicken recipes for more ways to use it. For other chicken dinners, try my greek yogurt chicken pasta or my high protein buffalo chicken dip.