Caramelized Onion and Mushroom Tart

By Alexandra Caspero on December 13, 2014

Caramelized onion and mushroom tart! The perfect vegetarian dish. Whole wheat tart layered with onions, mushrooms, and gorgonzola cheese.

You know those dishes you have for the first time in a restaurant and then spend hours and hours afterward in the kitchen trying to recreate? This is that recipe.

After having the #bestmealever in Vegas a few weeks ago, my dreams have been haunted by mushrooms. Perfectly browned mushrooms to be exact, paired with sweet caramelized onions and gorgonzola cheese. Which, is ironic in itself because if you would have asked me last month —> I don’t even like gorgonzola cheese. But then I tried that pizza, and it’s been downhill ever since.

Caramelized Onion And Mushroom Tart! The Perfect Vegetarian Appetizer, Side Or Main Dish. Whole Wheat Tart Stuffed With Onions, Mushrooms, And Gorgonzola Cheese. | Www.delishknowledge.com

When Bob’s Red Mill asked me to create a holiday recipe with whole wheat flour, my mind immediately went sweet. Maybe apple pie, pumpkin muffins, or cranberry bread? But then I took a quick peek at my recipe calendar for December and almost fell outta my chair.  Umm…I think I can hit the pause button on the sweet front (the past two weeks have brought us ginger chocolate truffles, apple pie cinnamon rolls, cranberry pecan thumbprints and pumpkin pie pecan bars.)

So, how about something savory instead?

Caramelized Onion And Mushroom Tart! The Perfect Vegetarian Appetizer, Side Or Main Dish. Whole Wheat Tart Stuffed With Onions, Mushrooms, And Gorgonzola Cheese. | Www.delishknowledge.com

I attempted to capture the flavors I loved so much at Giada’s restaurant and place them in a healthier tart.  Great success!  This tart works either plated as a signature vegetarian entree or served in reduced portions for small plates or appetizers. Pair with a simple side salad, and dinner is served.

There are a few steps involved, and while it might sound complicated, I promise it’s not. As long as you have the ingredients and a little time to enjoy in the kitchen, it’s not much of a challenge.

Caramelized Onion And Mushroom Tart! The Perfect Vegetarian Appetizer, Side Or Main Dish. Whole Wheat Tart Stuffed With Onions, Mushrooms, And Gorgonzola Cheese. | Www.delishknowledge.com

This crust is one you will be making over and over again, regardless of the filling. It’s the perfect base for vegetable tarts or quiches. If you favor sweet over savory, sub the dried thyme for a pinch of sugar.

The base is a traditional olive oil tart crust made with whole-wheat flour. Whenever I’m baking I like to add at least a 1:2 ratio of whole-wheat flour to all-purpose flour. Whole wheat flour is ideal for baking and can be combined with regular flour to create a healthy twist on your favorite baked goods. Every recipe, even a delicate pastry like this tart, can benefit from a bit of whole wheat flour.

Plus, whole wheat flour is a robust, full-flavored flour that contains vitamins, minerals and protein. It pairs perfectly with this hearty filling of mushrooms, onions, and a little cheese. For my vegan and dairy-free friends, try this tart with my creamy-garlic sauce instead of the gorgonzola.

Caramelized Onion And Mushroom Tart! The Perfect Vegetarian Appetizer, Side Or Main Dish. Whole Wheat Tart Stuffed With Onions, Mushrooms, And Gorgonzola Cheese. | Www.delishknowledge.com

Either way, this tart is a show-stopper!

Try it yourself using Bob’s Red Mill Whole Wheat Flour. Click here for a $1 off coupon!

If you try this recipe, let me know! Leave a comment, rate it, and tag your Instagram photos with #delishknowledge . I absolutely love seeing your creations. Happy cooking! 

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Caramelized Onion And Mushroom Tart! The Perfect Vegetarian Appetizer, Side Or Main Dish. Whole Wheat Tart Stuffed With Onions, Mushrooms, And Gorgonzola Cheese. | Www.delishknowledge.com

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Caramelized Onion And Mushroom Tart! The Perfect Vegetarian Appetizer, Side Or Main Dish. Whole Wheat Tart Stuffed With Onions, Mushrooms, And Gorgonzola Cheese. | Www.delishknowledge.com

Caramelized Onion and Mushroom Tart

  • Author: Alex Caspero
  • Prep Time: 30 minutes
  • Cook Time: 20 minutes
  • Total Time: 50 minutes
  • Yield: 8 slices 1x
  • Author: Alex Caspero
  • Prep Time: 30 minutes
  • Cook Time: 20 minutes
  • Total Time: 50 minutes
  • Yield: 8 slices 1x
  • Author: Alex Caspero
  • Prep Time: 30 minutes
  • Cook Time: 20 minutes
  • Total Time: 50 minutes
  • Yield: 8 slices 1x
Scale

Ingredients

  • 1 cup Bob’s Red Mill whole wheat flour
  • 1 cup all-purpose flour
  • 1 tsp. salt
  • 1 tsp. dried thyme
  • 1/4 cup olive oil
  • 1/2 cup cold water
  • 1 tsp. oil
  • 1 onion, thinly sliced
  • 16 oz. mushrooms, thinly sliced
  • 1/4 tsp. red pepper flakes (optional for an extra kick)
  • salt/pepper
  • 3/4 cup gorgonzola cheese

Instructions

  1. Combine the flour, salt, and thyme in a large bowl. Drizzle in the oil and mix well with a fork. Drizzle in the cold water and mix until the liquid is absorbed. Lightly knead the dough into a ball and then turn dough out onto a pastry board or cutting board and continue to knead a few times until it comes together. Wrap with plastic wrap and place in the fridge for 30 minutes.
  2. While the tart is cooling, prepare the onions and mushrooms.
  3. In a large sauce pan, heat the oil over medium heat. Add the onions and a pinch of salt. Stirring often, let the onions cook until reduced and browned, about 20 minutes.
  4. Remove the onions from the pan and add the mushrooms in a single layer. Cook the mushrooms over medium heat and cook until browned on both sides. Add in a pinch of freshly ground black pepper and red pepper flakes (if using).
  5. Remove the dough from the fridge and roll until a large circle, about 1/4 inch thick.
  6. Press into a lightly greased tart pan, removing any excess dough around the edges.
  7. Sprinkle on 1/2 of the cheese and then layer in the onions and mushrooms.
  8. Cover with remaining cheese and place in a 400 degree oven and bake for 20-25 minutes until golden, hot and bubbly.
  9. Serve warm or at warm temperature.

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Meet Alex Caspero

Alex Caspero is a Registered Dietitian, New York Times Bestselling Chef, and mom of two. She aims to cut through the nutrition noise by providing real-life, nourishing tips for body and mind. Learn more about Alex.

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    1. Whitney
      June 6, 2021 AT 8:21 am

      Now that was a good mushroom tart! I liked the dough – it wasn’t greasy and absorbed liquids without getting mushy. I liked that there weren’t a lot of exotic ingredients (my husband brought home two huge containers of button mushrooms from Costco I needed to use up!) I think the balance between mushrooms and onions was spot-on; neither dominated. I didn’t have Gorgonzola in the fridge so I substituted a combination Cambozola and Feta and I think I got a comparable flavor out of those. Thank you for a simple, delicious recipe!






      1. Alex
        June 6, 2021 AT 12:10 pm

        So glad you liked it!

    2. Jean Markey-Duncan
      November 30, 2019 AT 9:36 am

      I want to make this ahead and freeze it. Anyone know it that is possible and how to heat it up?

      1. Alex
        November 30, 2019 AT 2:33 pm

        Hi Jean, Shouldn’t be a problem- I’ve made tarts and frozen them successfully before, though haven’t done this one. Place the assembled tart, uncovered, on a level surface in the freezer; freeze for at least 8 hours, then wrap the frozen tart carefully: I’d wrap in plastic wrap and then in aluminum foil. Remove the tart from the freezer, unwrap and place on baking sheet. Bake (from a frozen state; middle rack) for 55 to 60 minutes or until heated through.

    3. Irene
      January 4, 2015 AT 3:48 pm

      I just tried this with a “cheater crust” i.e, prepared pie shell dough since I did not have any wheat flour on hand and it turned out great. Surprisingly quick to come together with delicious results!

      1. DK
        January 5, 2015 AT 6:22 am

        So glad you liked it! Thanks for sharing!

    4. Amy @ Amy’s Healthy Baking
      December 17, 2014 AT 1:41 am

      Oh gosh girl, you’re my hero for deciding against something sweet in favor of savory. No way could I do that! And caramelized onions + cheese = best thing ever. So glad you had that dish in Vegas so you could create this gorgeous one! Pinned!

    5. Dana | fresh simple five
      December 15, 2014 AT 12:27 pm

      Yum! I had a mushroom flatbread a few weeks back and it was absolutely to die for. This recipe totally reminds me of that. Can’t wait to try this one.

    6. Lauren Gibson
      December 14, 2014 AT 3:39 pm

      I too adore mushrooms (and gorgonzola). Looking forward to including this in my holiday cooking- thanks!

      1. DK
        December 16, 2014 AT 11:01 am

        Me too! It took me a little while to get into gorgonzola but now I love it- especially paired with mushrooms!

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