Classic Cauliflower Au Gratin Recipe

March 15, 2020 (Last Updated: August 12, 2020) - As an Amazon Associate I earn from qualifying purchases.

This Classic Cauliflower Au Gratin is a simple and cheesy side dish. Using a traditional French Mornay sauce, we turn the simple cauliflower into a casserole with loads of flavor. Learning how to make a great Au Gratin is essential for any home cook and this recipe gets you started on the right track with our Classic Cauliflower Au Gratin recipe.

Overhead shot of casserole dish containing classic Cauliflower au Gratin - Image.

Classic Cauliflower Au Gratin Summary

This really is a fancy French dish, but don’t let that scare you. Despite the fanciness, it is cheesy vegetables and tastes awesome. This recipe should be welcome from the most ornate dinner to the most humble meals. The star of our Au Gratin really is the cauliflower. We then introduce it to its main supporting cast of a delicious and classic French cheesy mornay sauce, and then top it off with a few bread crumbs. Then, some more cheese just for good measure. Finally, we finish it off in the oven before it hits your dinner table.

The entirety of this recipe can really be summarized in four steps. First, we cook the cauliflower, which is really as simple as boiling a head of cauliflower for a while. 

Then, we make the mornay sauce, but this can be done while the cauliflower is cooking. Mornay sauce might sound fancy, but it really isn’t a big deal.

Third, we cut the cauliflower and assemble the ingredient. Since we have already made the Mornay sauce and cooked the cauliflower, this really is just mixing our sauce with cheese and then topping it off with bread crumbs and more cheese.

Finally, just bake the stuff! It really is a simple dish and does not take that many steps to complete. 

Boiling the Cauliflower

I boil the whole head of cauliflower, but do prep the head just a bit. I cut off all the leaves and compost them OR save them for my dog as a treat. She loves em. 

Make sure that you are using a pot that is big enough to contain your whole cauliflower. Additionally, make sure that you leave enough room in your pot so that it can comfortably boil and won’t overflow. 

Once the water reaches a soft boil, I add the cauliflower and let it cook for about 15 minutes or until it is tender. I test its tenderness by just poking it with a fork.

When the cauliflower is done, I remove it and allow it to cool until it can be handled. It will be hot, so you will either need to let it sit for about five minutes or run it under cold water.

Mornay Sauce

Mornay Sauce is a classic French sauce. We start off with a bechamel sauce, which is one of the five classic mother sauces. Then, we add in Swiss Cheese. Some versions of Mornay sauce include parmesan and/or gruyere, but we are just sticking with Swiss. In addition, we add a pinch of pepper and cayenne to the mix just for a put of pop.

The thing about learning sauces like this is that they can be used for so much more than any individual dish. Even this Mornay sauce from this recipe could be translated to so many other ‘au gratin’ recipes. You could try broccoli or potato or really whatever enterest your imagination.

Not only can you use Swiss cheese, like we do in this recipe, but you can also experiment with other cheese. Mornay traditionally can include gruyere cheese and parmesan, but that shouldn’t limit you either. Cheddar, pepper jack, or really any meltable cheese is worth experimenting with.

Learning to create the bechamel sauce will also open up windows for you. As soon as you learn how to make a bechamel sauce, you just have a bunch of cooking options open up to you. Boxes of things like Hamburger Helper or Mac n Cheese might start looking crazy to you, as you might learn just how easy making sauces can be.

It Is A Casserole

This is a casserole and we have written about casseroles and hot dishes before. I enjoy discussing the differences between hotdish and casserole. As a Midwesterner, hotdish is definitely part of our food culture and they share the same space as a casserole, but there can be a difference. You are going to have to read my article for more information.

Assembling the Cauliflower Au Gratin

Adding the sauce and the cauliflower is simple enough, right? Then, on top, we add our bread crumbs and extra cheese. This will give the Cauliflower Au Gratin a nice topping that will melt during the bake. 

Cauliflower Au Gratin Process Shots
  1. Making the mornay sauce.
  2. Mixing the cooked cauliflower with the mornay sauce.
  3. Getting ready to get this dish in the oven. Topping the Cauliflower with bread crumbs and shredded cheese.

Cauliflower Au Gratin Tips

  • Remove the leaves before you boil the cauliflower. Your dog might like them as a treat. 🙂
  • Use quality bread crumbs for the best result
  • Layer your sauce in the casserole dish. Mornay sauce, the cauliflower, more mornay sauce.
  • Bake until heated and cheese on top looks nice and melted. About 25 minutes.

Tools I Used In This Recipe

Scooping Cauliflower Au Gratin out of casserole dish.

Did You Make This Au Gratin?

Let me know how it went. Cheesy goodness is always a welcome thing, right? I do, however, want to know how this recipe went for you. Leave me note in the comments section below and don’t forget to share this on Facebook and Pinterest. Making these recipes is really fun for me and when you share my recipes, it helps me make it just a little more worthwhile. Of course, if you want to get updates from me via email, make sure to subscribe to get our email.


Classic Cauliflower Au Gratin Recipe

Overhead view of a casserole dish of Cauliflower Au Gratin Casserole.

This Cauliflower Au Gratin is a classic, tasty, and simple casserole dish. It is great for any holiday or just a dinner side where you want something special.

  • Author: Ben Myhre
  • Prep Time: 10 minutes
  • Cook Time: 1 hour
  • Total Time: 1 hour 10 minutes
  • Yield: 4 Servings 1x
  • Category: Casserole
  • Method: Baking
  • Cuisine: French


  • 1 whole cauliflower, cleaned and green leaves removed
  • 2 tablespoon butter 
  • 3 tablespoon flour 
  • 2 cups milk 
  • 3 ounces (about 1.5 cups) Shredded Swiss cheese
  • 1/2 teaspoon salt
  • 1/4 teaspoon pepper
  • 1/4 teaspoon cayenne
  • 1/2 cup Italian Bread Crumbs


  1. Preheat oven to 375 Fahrenheit
  2. Fill a large pot full of water and bring to a soft boil
  3. Add Cauliflower and cook for 15 minutes or until tender when you put a fork in it.
  4. Remove from hot water and as soon as cauliflower is cool enough to handle, cut florets into bite sized pieces. 
  5. In sauce pan, heat butter on medium heat until melted
  6. Add flour to butter and mix. It will appear like a thick paste. 
  7. Slowly add milk and stir well. The goal is to integrate the butter, flour mixture with the milk. Turn heat up to medium high.
  8. Heat and stir until sauce thickens. Continue stirring until sauce starts to thicken.
  9. Once thickened add half of the cheese and mix. Remove from heat and continue to mix for a minute to ensure dairy doesn’t scald.
  10. Add salt, pepper, and cayenne to sauce.
  11. In casserole dish, add 1/3 sauce, cauliflower, and then the rest of the sauce, ensuring to cover all florets.
  12. Spread breadcrumbs evenly over top.
  13. Spread remaining cheese evenly over top.
  14. Bake in oven for 40 minutes.
  15. Remove from Oven and Serve.


  • Remove the leaves before you boil the cauliflower. Your dog might like them as a treat. 🙂
  • Use quality bread crumbs for the best result
  • Layer your sauce in the casserole dish. Mornay sauce, the cauliflower, more mornay sauce.
  • Bake until heated and cheese on top looks nice and melted. About 25 minutes.


  • Serving Size: 1/4 of total made
  • Calories: 295 kcal
  • Sugar: 11 g
  • Sodium: 558 mg
  • Fat: 15 g
  • Saturated Fat: 9 g
  • Unsaturated Fat: 4 g
  • Trans Fat: 0 g
  • Carbohydrates: 27 g
  • Fiber: 5 g
  • Protein: 16 g
  • Cholesterol: 35 mg

Keywords: Cauliflower Aug Gratin

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