Skip to content

Caramelized Onion & Roasted Cauliflower Tart

April 16, 2011

I can take no credit for this recipe. It comes from Deb over at Smitten Kitchen (she adapted it from Bon Appétit). I first made it, many months ago, and it’s pretty much perfect. It’s rich, decadent, and absolutely delicious. Seriously, you will be in heaven from the moment you put the first bite in your mouth. And you won’t be able to stop eating it. It’s that good.

I’m posting this recipe for a couple of reasons:

(1) If you haven’t made this tart yet, you really should. Like tonight. Or tomorrow. But don’t wait any longer than that—trust me, your taste buds will thank you.

(2) This recipe is a great lesson in how the delicious flavors in one dish can really inspire you to create something new and different. That’s what happened to me. I loved the flavors in this tart so much that I really wanted to use them as inspiration to create a new recipe. First, I tried a tart-inspired panade. It didn’t come out so well (it was just—meh). I may try revamping that idea at some point, but my first stab at the panade just wasn’t blog-worthy. And it certainly didn’t pay proper homage to this delectable tart.

Next, I decided to try a tart-inspired soup. And this one did pay proper homage to the tart. It was ridiculously delicious. So delicious in fact that I was in heaven from the moment I put the first bite in my mouth. And I wasn’t able to stop eating it. Just like the tart. A success! And a blog-worthy success at that. I’ll be posting about this soup very soon. In the meantime, you really should make this Caramelized Onion & Roasted Cauliflower Tart. Like, right now.


Adapted, barely, from Smitten Kitchen (adapted from Bon Appétit)

1 homemade tart shell (recipe below)
1 large head cauliflower (about 1 lb.)
1 large yellow onion
1 8 oz. package mascarpone cheese
1 cup grated Gruyère
2 tablespoons grated parmesan
1/2 cup heavy cream
2 large eggs
truffle oil
olive oil
dijon mustard
pinch of ground nutmeg
salt & pepper

Preheat the oven to 425°F.

Remove the stem and outer leaves from the cauliflower, and cut into florets. Place on a rimmed baking sheet, and toss with a little olive oil (about 1-2 tablespoons), salt, and pepper (to taste). Roast, tossing occasionally with a spatula, until just starting to turn golden at the edges—about 20 minutes. Remove from oven, and set aside to cool. Reduce the oven temperature to 350°F. Once the roasted cauliflower is cooled, thinly slice the florets (about 1/4 inch thick), and toss with a light drizzle of truffle oil. Set aside until you’re ready to assemble the tart.

While the cauliflower is roasting, caramelize the onion. Halve the onion, then thinly slice. In a large pan over medium-high heat, heat a couple splashes of olive oil. Add the onion, along with a little salt and pepper. Cook (stirring occasionally) for about 7 minutes, until the onion is translucent and just beginning to turn golden. Reduce the heat to low, and cook (stirring occasionally) until the onions are a deep golden color and caramelized, about 20 minutes. Once done, set aside until you’re ready to assemble the tart.

While you’re waiting on the onions and the cauliflower, mix together the eggs, mascarpone, and cream—along with salt and pepper, to taste. Next, add in the Gruyère, and stir to combine. Set aside.

Now you’re ready to assemble the tart. Place the pastry shell on a rimmed backing sheet, to catch any drips. Using a pastry brush, coat the bottom of the pastry shell (recipe below) with dijon mustard. Use a light touch here—the dijon mustard layer should only be about an 1/8 inch thick. Next, spread the caramelized onions evenly across the bottom of the pastry shell, and then top with the roasted cauliflower. Pour the mascarpone and cream mixture over caramelized onions and roasted cauliflower. Finally, sprinkle the top of the tart with 2 tablespoons grated parmesan. Place the tart (still on the rimmed baking sheet) in the oven. Bake until the tart is a lovely golden color, and the center is set—about 40 minutes. Remove from the oven, and cool on a wire rack for 15 minutes before serving.


From Smitten Kitchen (adapted from Le Pain Quotidien)

1 1/4 cups flour
1 tablespoon plus 2 teaspoons cornstarch
1/4 teaspoon salt
6 tablespoons butter, diced
1 egg

Combine the dry ingredients in a large bowl. Using a pastry blender (or two forks), cut the butter into the flour mixture, until it resembles small peas (see photo). Next, add the egg, and mix everything together with a fork, until a dough begins to form. At this point, the mixture will still be loose and very floury. To make it come together, get your hands in the bowl, and knead it together until it forms a smooth ball (see photo).

Next, on a lightly floured surface, roll out the dough to a 12-inch circle. Fold the dough in half, then in half again. Gently pick it up, and place in a 9-inch tart pan and unfold (folding the dough is simply an easy technique for transporting the dough to the pan without damaging it). Press the dough into the fluted edge of the pan, and trim the edges with a paring knife. Refrigerate for at least 30 minutes.* No parbaking needed!

* Make the dough before you start cooking the ingredients for the tart. By the time the cauliflower is roasted and the onions are caramelized, the tart will be ready for the oven as well.

5 Comments leave one →
  1. Martha permalink
    April 29, 2011 12:42 pm

    Hi Kristin! This is Kaitlin Kalna’s friend Martha. We haven’t seen each other since her wedding, but I was at a loss for recipes for an Easter lunch last week and Kaitlin pointed me in direction of your blog. I tried this tart and it was a big hit! So your tasty recipe has at least gone bi-coastal, as it was enjoyed by many in Medford, Massachusetts. I love the touch of dijon, and the white truffle oil adds a rich flavor to the cauliflower. It’s rich, but not overpowering. Soooo yummy! Thanks!

  2. September 25, 2011 3:42 am

    Mmmmmm, this is my sort of tart. I simply adore roasted or seared cauliflower, but with onion and pastry and creamy eggs and more golden brown bits? Bravo.

    • September 27, 2011 11:20 am

      Oh it’s so very yummy. One of those dishes you’re just really happy that you’re eating (and proud that you made!). Definitely give it a try!


  1. Creamy overnight oats (no-cook) for busy people who still want morning deliciousness « Two Spoons
  2. Macarons with not an almond in sight « Two Spoons

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: