Pesto Cauliflower Casserole

Pesto Cauliflower Casserole
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pesto cauliflower casserole
We would’ve liked for the bright green color to hold, but it still tasted great!

With fresh pesto in the house, we were looking for ways to use it. Sure, we could’ve quickly stirred it into pasta, but we decided that we’d get a bit more veggiefied, and have it stirred into cauliflower. But, even that didn’t sound right, so we thought that we’d stir it into cauliflower and bake it. Oh, and with bread crumbs on top (we currently have several quarts of bread crumbs from when we trimmed the crusts of sandwiches we made for the younger set). Yeah, that sounds better than simply stirring pesto into cooked cauliflower.

So, we took some techniques we learned from making Cauliflower Gratin,  went to work, and, before we knew it, the casserole was ready for the oven.

Awesome Pesto Cauliflower Casserole

Yield: 4 servings

Awesome Pesto Cauliflower Casserole


  • 1/2 head cauliflower cut into 3/4 to 1 inch pieces
  • 1 Tbs salt
  • 1 tsp white wine vinegar
  • Kosher salt
  • 1 Tbs unsalted butter, plus more for greasing
  • 2-3 Tbs finely diced white onion
  • Freshly ground black pepper
  • 1 Tbs all-purpose flour
  • 1 cup milk
  • 1 cup pesto
  • 1/2 cup seasoned bread crumbs

Abbreviated Instructions

Preheat oven to 350°F. Lightly grease an 8x8-inch baking pan.

In a large saucepan over high heat, bring about 2-3 quarts of water to a full boil. Add salt and vinegar and stir to dissolve. Add cauliflower pieces and boil, reducing heat as needed, until tender, about 3-5 minutes. Drain completely and lightly season with kosher salt. Transfer to prepared baking pan and spread into an even layer.

Melt butter in the same saucepan over medium heat. Add onions, sprinkle with salt and pepper, and cook until translucent, about 5 minutes. Add flour and stir to make a roux. Cook, stirring continuously, for about 1 minute.

Add milk and cook, stirring often, until mixture thickens and bubbles. Reduce heat and cook for 5 to 6 minutes more to remove the raw flour taste.

Stir in pesto and pour over cauliflower, stirring to coat.

Top with bread crumbs, cover with baking parchment (preferred) or foil, and bake 30 minutes. Remove parchment and bake an additional 15 minutes.

Stir in pesto.

Ingredient discussion:

seasoned breadcrumbs
Simple seasoned bread crumbs made with salt, pepper, and dried basil.

We can already hear people saying, “a cup of pesto? That stuff is expensive!” Yes, if you buy it already made it is expensive, but if you make it yourself, not so much. We’ve used a variety of greens, different cheeses, changed up the nuts, all based on what we had on hand to make pesto. It always turns out pretty well. Don’t have white wine vinegar? Use plain white vinegar or omit; it’s only there to keep the cauliflower white, and, with this sauce, you won’t see the cauliflower, anyway. For the seasoned breadcrumbs, we simply stirred salt, pepper, and dried basil into plain breadcrumbs and went for it.

Procedure in detail:

Preheat oven to 350°F. Butter an 8×8-inch baking pan and set aside.

cooking cauliflower
It’ll take a few minutes for the water to come back to a boil.

Cook cauliflower. Bring a large saucepan with 2-3 quarts of water to a full, rolling boil over high heat. Add the tablespoon of salt and vinegar, stirring to dissolve. Add the cauliflower and boil, reducing the heat as needed, until the cauliflower is nearly done. It can still be a bit underdone in the middle as it’s going to be baked later. We test by spearing a piece with a fork and tasting it.

Drain and season. Drain the cauliflower in a colander and allow it to sit for a few minutes. Sprinkle with just a bit of kosher salt to bring out the flavor. Again, taste test a floret to determine if you have enough salt. Let the cauliflower cool for another couple of minutes, then transfer to the prepared baking dish.

making roux
Roux is a fancy term for flour cooked with fat and used to make a thick sauce.

Make roux. Melt butter in the same saucepan — no need to wash — over medium heat. Add onions, sprinkle with a bit of salt and pepper to start them cooking and add some flavor, and cook, stirring often, until the onions are translucent, about 5 minutes. Add flour, stir to absorb all the butter and coat the onion pieces, and continue to cook for about a minute. Don’t let the flour brown.

making pesto sauce
Here you can see the thickened bechamel sauce that we use to make the pesto sauce.

Make sauce. Add the milk and stir (or even whisk) until smooth and uniform. Continue to cook, stirring, until the mixture bubbles and thickens, then reduce heat to a simmer and cook for about 5-6 minutes more. This additional cooking eliminates the raw flour taste of the sauce. Finally, stir in pesto to finish the sauce. Feel free to taste and add more salt and pepper as needed.

adding sauce
You could put the cauliflower in the pan of sauce and stir to coat, but we did it this way.

Stir to coat. Pour the sauce over the cauliflower and stir until well- coated. Spread the mixture into an even layer in the pan.

Ready for the oven
The breadcrumbs will make for a crispy topping on the pesto cauliflower casserole.

Top with breadcrumbs. Sprinkle breadcrumbs over the casserole and cover with baking parchment — we place a sheet over the pan and clip it in place with a couple of metal spring-load clips not unlike small clothespins — or aluminum foil.

Bake. Bake covered for 30 minutes, or until bubbly, then remove the covering and bake 15 minutes more to crisp the breadcrumbs.

We loved the flavor of this dish. Bright and full of flavor that stood out. The sauce was such that we were grateful to have some bread with dinner to sop it up. And, it was so rich from the cheese and olive oil in the pesto that we were quite content to save about half of the casserole for the next day. The only thing we didn’t like was that cooked basil no longer has that bright green color. For that alone, four stars.

Worth the trouble?

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