Creamy Cauliflower Broccoli Au Gratin

Look no further, this cauliflower broccoli au gratin recipe not only satisfies but will also impress. It's creamy, cheesy and spiced just right! It's a side dish that your family will love!

I originally posted this recipe in 2020, right after I had my daughter. Why is that important you ask– a good friend of mine introduced me to Trader Joe's Cauliflower and Broccoli Au Gratin while pregnant. I took one bit and I was in heaven. So of course I had to re-create it.

This might just be the best cauliflower broccoli au gratin recipe that I have ever had. It's the kind of recipe that satisfies without weighing you down (talking to you au gratin potatoes.) This is a recipe that is on repeat and I'm certain it will for you too.

Why You'll Love This Cauliflower Broccoli Au Gratin Recipe

• Insanely creamy
• Packed with flavor from the spices and cream sauce
• Ridiculously cheesy, as an au gratin should be!
• The cheese cause to cauliflower and broccoli ratio is perfect
• Crunchy breadcrumb topping takes it over the top

Vegetable Au Gratin Ingredients

• Vegetables: Traditionally au gratin is made with potatoes but we're swapping them out for a combination of broccoli and cauliflower florets. You can either buy them pre-cut or cut them yourself– you just want all pieces to be roughly the same size.
• Butter: Butter is in the base of the cheese sauce and used in the breadcrumb topping, adding so much flavor.
• Flour: Using flour helps thicken the cheese sauce just like in this slow cooker chicken and rice soup– not a cheese sauce it has the same job, thicken.
• Milk: The milk begins the sauce and gradually thickens as it cooks.
• Shredded Cheese: We're using parmesan and cheddar cheese in this recipe. Though, it's a pretty forgiving recipe so you can always use what you have on hand.
• Spices: Back to the basics here but each offers just the right amount of spice– salt, pepper, garlic powder and onion powder.
• Breadcrumbs: The star of that breadcrumb topping that gets crispy as it bakes. Do yourself a favor and don't forget this step.

How To Make Cauliflower Broccoli Au Gratin

Have you ever made au gratin from scratch before? It looks intimidating but don't fret, it's easy. I also include some tips and tricks further down to make it even easier!

1. Steam the veggies: Steam or boil the cauliflower and broccoli until just tender— you don't want them fully cooked since they will finish in the oven.
2. Begin the cheese sauce: Melt the butter on the stove, then add flour. The flour soaks up the butter making a "roux." Cook the roux for 1 minute, this helps cook out of the flour taste. If you're not familiar with a roux, pronounced "roo", it's a way to thicken things like gravy, sauce, macaroni and cheese or soup! Making a roux is very simple with equal parts butter and flour, letting it cook down and then adding the liquid (in this case, the milk.)
3. Add the milk and spices: Whisk in the milk, salt, pepper, garlic powder, and onion powder. Bring it to simmer and whisk in the cheese until smooth.
4. Combine: Add a few spoonfuls of the cheese sauce to the bottom of the baking dish. Then, add the veggies. Pour the remaining cheese sauce on top and gently stir together.
5. Make the breadcrumb topping: Melt the butter and stir in the Panko. Sprinkle over the top.
6. Bake: Bake for 17-20 minutes until bubbly and slightly brown on the top.

Tips & Tricks

While this is an easy recipe, here's a few tips to make it even easier!

1. Use steam-in-bag vegetables– that's right, use that shortcut! For those extra busy nights or you really just don't feel like pulling out a pot to steam vegetables... there's no shame. I've done it a handful of times! However, if using this option, steam for 1 minute less than it says since the'll finish cooking in the oven.
2. Make the breadcrumb topping while the vegetables steam. No matter how you steam the vegetables, do this step in parallel. It's quick but another step done ahead of time.
3. Use whole milk for the cream sauce. In a pinch I've used 1% or 2% milk but it's THAT MUCH BETTER when you use whole milk.

What Cheese Do I Use?

For a truly remarkable au gratin, use a combination of cheeses. I recommend using white cheddar and parmesan for the best flavor. Grate it at home if you can, so it's soft and fresh– pre-shredded has additives to make it a bit sturdier. I love this cheese grater if you're in the market for one!

We're looking for this level of a creaminess:

I can say with 100% certainty that this cauliflower and broccoli au gratin is absolutely dynamite.

More Side Dishes

• Oven Roasted Asparagus
• Oven Roasted Potatoes
• Brown Butter Garlic Mushrooms
• Homemade Buttermilk Biscuits
• Classic No Knead Bread

Creamy Cauliflower and Broccoli Au Gratin

Author: Christina

Prep Time: 15 minutes minutes

Cook Time: 30 minutes minutes

Total Time: 45 minutes minutes

Yield: 6 servings

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Description

If you're searching for a side dish that satisfies and impresses, look no further. This cauliflower and broccoli au gratin is creamy, cheesy, and spiced just right! It's a recipe that you and your family will love!

Ingredients

 

Au Gratin

• ▢ 3 cups cauliflower florets, cut into like-size florets
• ▢ 3 cups broccoli florets, cut into like-size florets
• ▢ 6 Tablespoons unsalted butter
• ▢ ⅓ cup all-purpose flour
• ▢ 2 ½ cups whole milk
• ▢ 1 ½ cups shredded white cheddar cheese
• ▢ ¼ cup shredded parmesan cheese
• ▢ 2 teaspoons salt
• ▢ 1 teaspoon freshly ground black pepper
• ▢ ½ teaspoon garlic powder
• ▢ ½ teaspoon onion powder

Breadcrumb Topping

• ▢ 3 Tablespoons unsalted butter, melted
• ▢ ¾ cup Panko breadcrumbs

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Instructions

• Steam or boil cauliflower and broccoli florets until almost tender— about 4 minutes. You don't want them fully cooked since they will finish in the oven. Set aside. Preheat the oven to 350°F. Light spray a 9x13 inch or 3-4 quart baking dish with non-stick cooking spray. Set aside.
• Make the cheese sauce: In a large saucepan, melt the 6 Tablespoons of butter over medium heat. Once melted, whisk in the flour to form a paste, also known as a "roux". Cook and whisk the paste for about 1 minute, this help cooks out the flour taste. Then, slowly whisk in the milk, salt, pepper, garlic powder, and onion powder. Allow the mixture to come to a simmer, then whisk in the shredded cheese until smooth. Remove from the heat.
• Add a few spoonfuls of the cheese sauce to the bottom of the baking dish. Then, add the cauliflower and broccoli. Pour the remaining cheese sauce on top of the cauliflower and broccoli and gently stir together, making sure the florets are covered.
• Make the breadcrumb topping: Melt 3 Tablespoons of butter and stir in the Panko. Sprinkle over the cauliflower and broccoli.
• Bake for 17-20 minutes or until bubbly and slightly brown on the top. If you're like me and prefer a crispier top, use the broiler for 1 minute after it bakes (keep an eye on it so it doesn't burn!)
• All to sit for 5 minutes before serving. 

Notes

1. Make Ahead & Freezing Instructions: To freeze, prepare the au gratin through step 3— save the breadcrumbs right before baking. Cover tightly and freeze for up to 3 months. Thaw 24 hours in the refrigerator, then top with breadcrumbs (if desired) and bake at 350°F for about 45 minutes or until warm throughout. 
2. Milk: Using whole milk is strongly recommended for the creamiest sauce though 1% or 2% works as well.
3. Cheese: Use a mix of freshly grated cheese for the best flavor and consistency. Pre-shredded cheese tends to be more dry.

Nutrition

Calories: 428kcal | Carbohydrates: 22g | Protein: 16g | Fat: 32g | Saturated Fat: 19g | Polyunsaturated Fat: 1g | Monounsaturated Fat: 8g | Trans Fat: 1g | Cholesterol: 88mg | Sodium: 1153mg | Potassium: 508mg | Fiber: 3g | Sugar: 7g | Vitamin A: 1291IU | Vitamin C: 65mg | Calcium: 429mg | Iron: 1mg

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