Healthy Broccoli Casserole

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Healthy Broccoli Casserole with a fresh broccoli, creamy cheddar cheese sauce, mushrooms, and crispy onions will be your new favorite holiday casserole. Plus you can prep it ahead of time!

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This delicious, lightened-up Broccoli Casserole is a mash-up of broccoli and green bean casserole that you will immediately love. It's made with tender crisp broccoli tossed in a homemade mushroom gravy (no canned soup!) topped with cheddar cheese and crispy onions.

It will fly off your holiday table and no one will ever believe this tasty broccoli casserole is actually healthy.

Growing up my Mom made this amazing broccoli casserole that was basically a combination of frozen chopped broccoli, cheddar cheese, mayonnaise, and cream of mushroom soup all covered in breadcrumbs. It was surprisingly delicious (given that ingredient list) but obviously isn't the healthiest of the freshest recipe.

I knew this holiday season, I wanted to create a healthier version of this dish.

While I normally would start from scratch to create this recipe, this year I wanted to start with my absolute favorite Healthy Green Bean Casserole. I have been making this recipe for the years and it is seriously the best lightened-up casserole recipe. However, I wanted to change a few things to incorporate the cheddar cheese that is typically found in broccoli casserole.

Let's talk about what makes this recipe so delicious. First, it starts with fresh broccoli instead of frozen. This ensures that your broccoli will have some crunch and texture. Frozen broccoli tends to get mushy. That is tossed with a creamy cheddar cheese sauce packed with mushrooms and plenty of garlic. Finally, everything is finished with another layer of cheddar cheese and tons of crispy red onions. So so good.

Broccoli casserole with crispy red onion, breadcrumbs, and mushrooms in a ceramic dish.

Key Ingredients

Here is everything you need to make this lightened-up broccoli cheese casserole.

  • Broccoli: Unlike most broccoli casseroles, this recipe uses fresh broccoli florets so the final dish has some texture and crunch. No mushy casserole here. For more contrast, swap in some fresh cauliflower florets for some of the broccoli. 
  • Red onion: Red onion is milder than white or yellow onions. It also has a beautiful color. Feel free to swap in shallots, sweet Vidalia onions, or traditional yellow onions.
  • Panko breadcrumbs: For the crunchy topping, Panko breadcrumbs are the perfect option. Use regular or whole wheat. Regular breadcrumbs also work, they just won't be quite as crisp. Gluten-free breadcrumbs or sliced almonds could also be used.
  • Baby Bella mushrooms: Fresh mushrooms replace the condensed mushroom soup usually used in this casserole. Any mushroom can be used. This is great with button mushrooms, portobello, or a variety. 
  • Garlic: The garlic adds a nice punch of flavor to the dish. Fresh garlic is best but minced garlic or garlic powder can be used.
  • Cheddar Cheese sauce: The cheese sauce in this recipe is made with whole wheat flour, chicken broth, milk, and cheddar cheese. Vegetable broth can be used for a vegetarian version. 

How to Make Healthy Broccoli Casserole

  1. Blanch the broccoli: Start by blanching the broccoli florets in boiling water for 3-4 minutes until they are bright green and just beginning to soften. Immediately remove them from the boiling water and place them in an ice bath to stop them from cooking. The broccoli won't cook completely in the casserole so this step ensures it is completely cooked in the final product.
  2. Make crispy onion topping: One of the best parts of this casserole is the crispy onion topping. Start by cooking the red onions in butter until they are tender but still have a bit of texture. Then cook the breadcrumbs in butter until they are nicely browned. Mix the browned, toasted breadcrumbs with the onions to make the topping.
  3. Make the mushroom sauce: Start by sauteing the mushrooms in butter and garlic. Once they are tender, add the flour and cook for one minute. This helps to thicken the sauce. Then add the chicken broth and stir until the flour dissolves. Make sure it fully dissolves for a smooth sauce. Add the milk and half the cheddar cheese. Simmer gently, stirring often, until it thickens. 
  4. Assemble the casserole: Add the broccoli florets to a prepared casserole dish. Pour the mushroom sauce on top and stir to coat the broccoli in the sauce. Then add a layer of cheddar cheese and the crispy onions and breadcrumbs.
  5. Bake: Bake the casserole at 375 degrees until the sides are bubbling and the onions are nicely browned. If needed, broil it for the last 2-3 minutes to get the top nicely browned. 

Recipe Ideas

There are lots of ways to make this broccoli casserole unique and exactly what your family will love.

  • Try a different cheese: Although I can't get enough cheddar cheese and broccoli, this will also work great with Parmesan cheese, pepper jack (for something spicy), Swiss, or any other cheese that melts well. You can also use a combination of cheeses. Basically, anything that would work in macaroni and cheese will work well here.
  • Add herbs or spices: Fresh herbs are a great addition to this dish. Dried herbs work great as well. Consider adding some thyme, rosemary, or Italian seasoning. You could also add some heat with red pepper flakes, smokiness with cumin, or extra flavor with onion or garlic powder. I find this works best when you add the herbs and spices to the mushroom sauce.
  • Use a different vegetable: If you aren't feeling the broccoli, you can make this with cauliflower, green beans, or even butternut squash. Just make sure to par-cook any vegetable you use. 
  • Make it gluten-free: Just substitute gluten-free flour and breadcrumbs.
  • Without onions: If you aren't a huge onion person, just leave them out. Top the casserole with a layer of cheddar cheese and toasted breadcrumbs. 

Make it in Advance

Broccoli casserole is a dish that can be prepped the day before to make holiday meal prep easier. Simply assemble the casserole and cover it with foil or plastic wrap and store it in the fridge. If possible, remove it from the oven 30-45 minutes before cooking to remove the chill. If not, just add 5-10 minutes to the baking time. 

Can I freeze broccoli casserole?

Personally, I don't recommend freezing this type of casserole because the broccoli and onion topping will get mushy. The sauce can also separate when you are reheating it. This is best eaten right after cooking and leftovers can be stored in the fridge for 3-4 days. Reheat in the microwave, a saute pan, or in the oven.

Can I use frozen broccoli?

Frozen broccoli can be used in place of fresh but the texture will be slightly different and a bit mushy. Start by cooking the frozen broccoli until just cooked. Immediately run it under cold water to stop the cooking. Dry it well to ensure your casserole isn't watery. Then use it as you would the fresh.

Can I add rice or pasta? What about Chicken?

To turn this into a main course, you can add some cooked rice or pasta. If you plan on doing this, make sure to double or triple the mushroom sauce. Then simply fold the cooked pasta (cooked until al dente) or cooked rice in with the broccoli. If you like, you can also add some cooked chicken as well.

Healthier casserole with broccoli, mushrooms, cheddar cheese, and crispy onions.

What to Serve with Broccoli Casserole

It should go without saying, that this is the perfect dish for Thanksgiving or any holiday serving. It goes great with turkey, ham, or any other holiday proteins. We also love pairing it with a simple store-bought rotisserie chicken or roasted chicken with cauliflower mashed potatoes and cranberry sauce. It feels like a holiday meal but is easy enough for a weeknight.

Looking for more broccoli recipes?

The Recipe
Healthy broccoli casserole with mushrooms, cheddar cheese, and crispy onions in a baking dish with a spoon.

Healthy Broccoli Casserole

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  • 2 lbs broccoli florets
  • 3 tbsp butter, divided
  • 1 red onion, thinly sliced
  • 1/2 cup Panko breadcrumbs
  • 8 oz baby bella mushrooms, sliced
  • 4 garlic cloves, minced
  • 3 tbsp white whole wheat flour
  • 1/2 cup chicken broth
  • 1 cup 2% milk
  • 1 cup shredded cheddar cheese, divided

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Preheat the oven to 375 degrees.


Bring a large pot of water to a boil. Add the broccoli and cook for 3-4 minutes until bright green and just tender. Add to a colander and toss with ice and cold water to stop them from cooking longer. Dry well.


Make the crispy onion topping. Melt 1/2 tbsp of butter in a pan over medium high heat. Add the onions and cook for 4-5 minutes until tender but still have thier shape. Remove the set aside in a bowl. Add another 1/2 tbsp of butter. Add the breadcrumbs and cook for 2-3 minutes until golden brown. Toss with the onions.


Make the mushroom sauce. Melt two tablespoons of butter in a pan. Add the mushrooms and cook for 4-5 minutes until tender. Stir in the garlic and cook for 1-2 minutes until fragrant. Stir in the flour and cook for about 1 minute until light brown. Add the chicken broth and stir until the flour dissolves into the broth. Add the milk and 1/2 cup cheddar cheese. Bring to a simmer and cook for 3-5 minutes until it thickens. Season well with salt and pepper.


Spray a 9 X 13 dish with cooking spray. Add the broccoli florets and pour the mushroom sauce on top. Stir together so the broccoli is coated in the sauce. Top with 1/2 cup of shredded cheddar cheese. Then add the crispy onions.


Bake for 20-25 minutes until casserole is bubbling and the onions are crispy and golden brown. If needed, you can broil for 1-2 minutes to brown the top more.

Nutritional Facts
Serving Size: 1/2-2/3 cup
Amount Per Serving
Calories 129
Calories from Fat 64
% Daily Value *
Total Fat 7g
Saturated Fat 4g
Monounsaturated Fat 0g
Polyunsaturated Fat 0g
Cholesterol 21mg
Sodium 111mg
Total Carbohydrate 12g
Dietary Fiber 2g
Sugars 3g
Protein 7g

* Percent Daily Values are based on a 2,000 calorie diet. Your daily values may be higher or lower depending on your calorie needs.

The Nutritional Values provided are estimates only and may vary based on the preparation method.

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About the author Meet Kristen McCaffrey
Hi, I’m the cookbook author, recipe developer, and food enthusiast behind Slender Kitchen. I am obsessed with making healthy food that is easy to prepare and absolutely delicious. Meal planning is my secret weapon and I hope I can make meal time easier for you with our tried and tested recipes and foolproof meal plans. Learn More
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