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Caramelized Onion + Leek Savory Tart with Herbed + Parmesan Cheese

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  • Author: Cosette Posko
  • Prep Time: 45 minutes
  • Cook Time: 35 minutes
  • Total Time: 1 hour 20 minutes
  • Yield: 1 tart 1x
  • Category: Savory Tart
  • Method: Baking
  • Cuisine: French


This savory onion tart is filled with caramelized onions, tangy goat cheese, parmesan cheese and topped with springy leeks. Inspired by Triple Threat Onion Galette recipe from Bon Appetit. 


Units Scale
  • 1 prepared pie dough crust, my favorite recipe is by Marie Saba if you are looking to make it homemade. Otherwise, choose your favorite store brand.
  • A few sprigs of fresh oregano, you can also sub fresh rosemary
  • 3-4 large onions, about 1.5 lbs sliced
  • 4 Tablespoons unsalted butter - 56 grams
  • 15 cloves of peeled garlic, keep whole
  • 1 teaspoon kosher salt*
  • 2-2.5 ounces of herbed goat cheese, softened at room temperature
  • 1/2 ounces of freshly grated parmesan cheese - about 15 grams + extra for crust
  • fresh ground pepper
  • 1 leek, cut into thin strips and cleaned well
  • 6-8 scallions
  • 1 egg, lightly beaten for egg wash


  1. Begin by preparing your pie crust - if you are making your own, I like to add some fresh oregano (or rosemary) when preparing. Once your dough is ready to use, roll out into a 13" diameter and place on a parchment lined half sheet pan. Place this into the freezer while you prepare the rest of your ingredients. 
    • 1 prepared pie dough crust, my favorite recipe is by Marie Saba if you are looking to make it homemade. Otherwise, choose your favorite store brand.
    • A few sprigs of fresh oregano, you can also sub fresh rosemary
  2. Slice 3-4 large onions, about 1.5 pounds. Onions just need to be on the thinner side, but nothing too fancy. Place sliced onions and 4 Tablespoons of butter into a 12-13" skillet on high heat. Allow the butter to melt and the onions begin to sweat, stirring every so often. This high heat allows the onions to begin to break down and slowly shrink. Continue on high heat for about 8 minutes.
    • 3-4 large onions, about 1.5 lbs sliced 
    • 4 Tablespoons unsalted butter - 56 grams
  3. After about 8 minutes of high heat, reduce to medium and cover your skillet. Covering allows more heat and steam to build up speeding the caramelization process up. Cover for 5 minutes then add your whole cloves of garlic and 1 teaspoon of kosher salt. Cover again.
    • 15 cloves of peeled garlic, keep whole
    • 1 teaspoon kosher salt*
  4. Reduce heat to medium-low and continue cooking onions for another 25-30 minutes, lifting lid and stirring every 5 minutes to ensure even cooking and deglazing of your pan. Allow the steam from the lid to drip into the pan to help deglaze.
  5. Once caramelized, set aside to slightly cool. Preheat oven to 425 degrees while you wait and begin assembling.
  6. Remove your pie disc from the freezer and spread your herbed goat cheese into a thin layer, leaving an inch border around your disc.
    • 2-2.5 ounces of herbed goat cheese, softened at room temperature
  7. Next grate your parmesan cheese into a thin layer on top of your herbed goat cheese - about 1/2 an ounce but feel free to measure with your heart!
    • 1/2 ounce of freshly grated parmesan cheese - about 15 grams
  8. Place your cooled caramelized onions next then sprinkle some black pepper.
  9. Prepare your leek, leeks carry a lot of dirt - trim the end then cut in half, then each half in half again so you have quarters. You want some thinner strips - then wash to make sure dirt is removed and dry. Trim your scallion ends and cut into thirds.
    • 1 leek, cut into thin strips and cleaned well
    • 6-8 scallions
  10. Lay your leek and scallions in various directions on top of your caramelized onions to create a pattern.
  11. Fold your edge over the leeks and scallions to create an edge for your tart.
  12. Brush the crust with a beaten egg and grate some additional parmesan. 
  13. Finally, drizzle the top of your leeks and scallions with a bit of olive oil. 
  14. Place in preheated oven and bake for 30-35 minutes until golden brown. 
  15. Allow to cool slightly, top with additional fresh oregano or rosemary, slice and enjoy!


  • The tart does not need much salt as the cheeses contain enough salt to carry the flavor. You can always taste your caramelized onions to make sure the flavor is where you want it.
  • As always, if you are using table salt - cut in half.
  • You can assemble your entire tart, freeze and bake from frozen - see storage and freezer section.