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Cauliflower should get a starring role in more dishes– it’s tasty when roasted, works well as a supporting cast member or the lead in the recipe, and it’s healthy. Paired with caramelized onions and a flaky crust, this tart lets the cauliflower shine once again.

Cauliflower itself is packed with vitamins and antioxidants, and some say it’s great for digestive and heart health as well. If you’re looking for ways to incorporate healthy veggies into your diet, this is one meal that does so perfectly, plus it’s vegetarian, so a bit more accessible to those with dietary restrictions.

Though this recipe calls for Gruyere, you can substitute Swiss cheese or a combo of fontina and Parmesan. If you want it to be a touch lighter, swap out mascarpone for a reduced-fat sour cream.

Cauliflower and Caramelized Onion Tart

(makes 8 servings)


  • 1 refrigerated pie crust or homemade tart shell (click here for a recipe)
  • 1 large head cauliflower, cut into florets
  • 1 large yellow onion, cut in half and thinly sliced
  • 1 8 -ounce package mascarpone cheese (substitute sour cream for a lighter version)
  • 1 cup grated Gruyere (or substitute Swiss OR fontina/Parmesan combo)
  • 2 tablespoons grated Parmesan
  • 1/2 cup heavy cream
  • 2 large eggs
  • Truffle oil (optional)
  • Olive oil
  • Dijon mustard
  • Pinch of ground nutmeg
  • Salt
  • Pepper
  • Sugar


  1. Preheat the oven to 425 degrees F. Toss the cauliflower with a generous amount of olive oil to coat, as well as salt and pepper to taste. Place the cauliflower on a baking sheet and roast for about 20 minutes, making sure to flip once or twice along the way. The florets should just be getting golden. Remove the florets from the oven and set aside. Lower the temperature to 350 degrees F.
  2. While the florets are roasting, youíll caramelize the onion. Cut the onion in half and thinly slice it, then add about a tablespoon of olive oil to a large pan over medium-high heat. Add the sliced onion as well as a dash of salt and pepper to the pan.
  3. Cook the onion for about seven minutes, stirring occasionally, until it gets tender and translucent — then reduce the heat to low. (Add a pinch of sugar once you reduce the heat for a little sweetness.) Then, let the onion slices cook on low until they become a deep golden or brown color– it takes about 20 minutes for them to caramelize. Stir them often enough so they don’t burn the bottom of the pan, but make sure they have enough time to sit in the oil and caramelize. Add a little water to the pan if they start to stick too much to the bottom.
  4. Once the cauliflower is cool, thinly slice the florets so they are about 1/4-inch thick. Toss with a drizzle of truffle oil (if desired) and set aside.
  5. Mix together the eggs, mascarpone, cream, nutmeg, and salt and pepper to taste. Then, add the Gruyere (or substitute) to the mixture.
  6. Press your crust into a 9-inch tart pan, trimming any excess from the edges with a knife. If the crust didn’t come refrigerated, you’ll want to refrigerate it for 30 minutes after pressing into the pan and before assembling the tart.
  7. Place the pastry shell on a rimmed baking sheet (to catch any drips) and coat the bottom of the pastry shell with Dijon mustard (the mustard layer should only be 1/8-inch thick). Then, spread the onions evenly over the bottom of the pastry shell, followed by the roasted cauliflower.
  8. Pour the cheese and cream mixture over the onions and cauliflower, and then top the tart with the grated Parmesan cheese. Place the baking sheet into the oven and bake for about 40 minutes ñ youíll want the top to be golden brown and the center to be set.
  9. Let the tart cool for about 15 minutes before serving.
  10. Enjoy!

Recipe adapted from Mission Delectable

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