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Cheesy Broccoli Cauliflower Casserole (Vegetable Au Gratin)

Enhance any meal or holiday table with this easy Cheesy Broccoli Cauliflower Casserole, a.k .a. Vegetable Au Gratin. Not just for the holidays, this makes a wonderful side dish year-round. It’s easy to make and perfect for adjusting to dietary needs, like keto, dairy-free and gluten-free.

Prep Time
15 mins
Cook Time
15 mins
Total Time
40 mins
Servings: 6 servings
Calories: 435 kcal
Course: Side Dish
Cuisine: American

Ingredients

  • 4 cups broccoli florets fresh is best
  • 4 cups cauliflower florets fresh is best
  • 2 tablespoons olive oil
  • ½ cup onion chopped or minced
  • 3 cloves garlic minced or pressed
  • 2 tablespoons all-purpose flour or sub with gluten-free all purpose flour or almond flour
  • 2 cups half and half sub with heavy cream, whole milk or other % or plant-based milk
  • 1 cup Swiss cheese shredded
  • 1 cup white cheddar shredded
  • ½ cup Parmesan Cheese + 2 tablespoons Parmesan cheese, freshly grated and divided
  • ¼ teaspoon ground nutmeg try fresh ground, so good
  • salt and pepper to taste
  • 2 tablespoons butter melted
  • ½ cup Panko bread crumbs or gluten-free panko

Instructions

    Cup of Yum
  1. Preheat the oven to 375° F (190° C). Lightly coat an 8x8, 9x9 or gratin baking dish with oil or butter.
  2. Add 1-2 inches of water into a large pot fitted with a steamer basket. Bring the water to a boil. Carefully add the broccoli and cauliflower, cover, and simmer until just crisp tender, about 5 minutes. Remove the basket from the pot and allow it to drain.
  3. Heat a medium saucepan or skillet to medium heat. Add the olive oil, allow it to warm a bit, and then add the onion and saute until translucent, about 5 minutes. Add the garlic and stir until fragrant, 30 seconds.
  4. Add the flour (or alternative) and stir constantly, until the mixture turns golden and thick.
  5. Slowly add the half and half, about ½ cup at a time, stirring constantly, adding more as it thickens.
  6. Once the sauce has thickened, lower the heat, and add the cheeses in small batches and stir until melted.
  7. Add the nutmeg and stir to combine. Add salt and pepper to taste. I used ½ teaspoon of each.
  8. Add the steamed broccoli and cauliflower to the sauce and stir to coat. Then pour the mixture into the prepared baking dish.
  9. Combine the melted butter, breadcrumbs and 2 tablespoons of parmesan cheese in a small bowl. Sprinkle over the top of the casserole.
  10. Bake for 25 minutes until bubbly and top is slightly golden, serve immediately.

Notes

  • Buy the blocks of white cheddar, Swiss, and parmesan cheese and grate yourself. Pre-shredded contains additives, and it doesn’t melt as nicely.● Fresh broccoli and cauliflower will give the best texture in this dish.● Whole milk can be substituted for half and half. You can also use 2% or skim milk, but it will be less creamy and rich.● Don’t overcook the veggies when steaming; they will cook more in the oven. Overcooking will result in mushy vegetables.● Add cooked chicken breast to the sauce with the vegetables to make this a main dish.● Broccoli and cauliflower can be bland vegetables; taste and add more seasoning if necessary.
  • Gluten-Free Broccoli and Cauliflower Casserole | Use a gluten-free brand of panko breadcrumbs and a gluten-free flour alternative in your sauce to make the dish gluten-free. Grate your own cheese, as pre-shredded packs have additives that often contain gluten. That is it!
  • Low-Carb Broccoli and Cauliflower Bake | Substitute almond or coconut flour for the flour to make the dish low-carb. Skip the panko breadcrumbs, or toss some pork rind crumbs with melted butter and sprinkle on top.
  • Add Protein | Add cooked chicken breast, turkey, rotisserie chicken, diced ham, or bacon to the sauce with the vegetables to make this a main dish. Leftover turkey from the holidays works, too!
  • Vegan Vegetable Au Gratin | All you need to do for a vegan or dairy-free version is replace the cheese, cream, and butter with your favorite plant-based products.

Nutrition Information

Serving 1serving Calories 435kcal (22%) Carbohydrates 19g (6%) Protein 19g (38%) Fat 33g (51%) Saturated Fat 17g (85%) Polyunsaturated Fat 2g Monounsaturated Fat 11g Trans Fat 0.2g Cholesterol 80mg (27%) Sodium 447mg (19%) Potassium 572mg (16%) Fiber 3g (12%) Sugar 7g (14%) Vitamin A 1184IU (24%) Vitamin C 88mg (98%) Calcium 538mg (54%) Iron 1mg (6%)

Nutrition Facts

Serving: 6servings

Amount Per Serving

Calories 435

% Daily Value*

Serving 1serving
Calories 435kcal 22%
Carbohydrates 19g 6%
Protein 19g 38%
Fat 33g 51%
Saturated Fat 17g 85%
Polyunsaturated Fat 2g 12%
Monounsaturated Fat 11g 55%
Trans Fat 0.2g 10%
Cholesterol 80mg 27%
Sodium 447mg 19%
Potassium 572mg 12%
Fiber 3g 12%
Sugar 7g 14%
Vitamin A 1184IU 24%
Vitamin C 88mg 98%
Calcium 538mg 54%
Iron 1mg 6%

* Percent Daily Values are based on a 2,000 calorie diet.