Caramelized Onion & Blue Cheese Tart

Hey Friends!
Sharing part 3 of 3 in my caramelized onion series! This Caramelized Onion & Blue Cheese Tart is rich and decadent. It makes for the perfect appetizer or side for all those upcoming parties this season. Just in case you want to play up an alternate version, skip the crust, and bake filling directly in a small baking dish. Serve with your favorite toasted baguette for a fondue – like experience. Your friends and family will be totally wowed.

If you just can’t get enough of richy, nutty onions in recipes, see this link for my French onion soup w/ gluten free parmesan garlic croutons. Here you can find my recipe for Caramelized Onion Frittata with Pancetta.

Enjoy! Let me know what you think by commenting below or sending a note on social.


Caramelized Onion & Blue Cheese Tart

This tart is rich and decadent. It makes for the perfect appetizer or side. Alternate version: skip the crust, and bake filling directly in small baking dish. Serve with your favorite gluten free toasted baguette for a fondue - like experience.


Gluten Free Crust

  • 95g (2/3 cup) brown rice flour
  • 75g (1/2 cup) gluten free flour blend, 1-1
  • 35g (1/4 cup) arrowroot flour
  • 1/4 teaspoon sea salt
  • 110g (1/2 cup or 1 stick) unsalted butter, cut
  • 1 egg yolk
  • 3-7 tablespoons ice water


  • 533g (6 cups / about 2 large ) yellow onions, thinly sliced
  • 28g (3 tablespoons) olive oil
  • 8 oz. (1 cup) heavy cream
  • 100g (½ cup) sour cream
  • 2 egg yolks
  • 80g (⅔ cup) gorgonzola cheese crumbles
  • 3 tablespoons arrowroot powder
  • ½ teaspoon salt
  • 2 pinches freshly cracked pepper
  • 2 ½ tablespoons hazelnuts, chopped
  • Optional: 3-4 medium shallots sliced in wedges


  • Grease one large deep dish pie pan.
  • Prepare crust: Combine the first 4 ingredients in the food processor and pulse to mix.
  • Add the cut butter pieces and pulse a few times through until butter is the size of peas and ingredients start to clump and hold together.
  • In a small bowl, whisk together the egg yolk and 3 tablespoons ice water with a fork.
  • Add it to the dough slowly while pulsing until a dough ball forms. Do not over pulse; stop as soon as it begins to clump and there are nearly no flour bits left. Add more ice water only if needed (dependent upon your elevation and the humidity levels in your kitchen). *You’ll want enough moisture in the dough to prevent cracking, so add water until it’s slightly sticky on your fingers.
  • Remove dough from bowl and place on lightly floured surface.Work gently into ball. Flatten to 1” disk. Wrap in plastic, chill in fridge for 20-30 minutes.
  • When chilled, roll the dough to about 1/8-inch thickness. Fill the pie pan(s) with the dough and cut off excess. Alleviate any cracks by pressing into place.
  • Place in freezer while you make the filling. This will help keep its shape during baking.
  • Prepare caramelized onions: In a large Dutch oven, heat 3 tablespoons olive oil over medium to medium high heat. Add half of the onions and cook, stirring occasionally for 3 minutes.
  • Add remaining onions. Season with salt and pepper and toss. Continue to cook, stirring occasionally, about every 3-5 minutes, until onions begin to stick to bottom of pot, stirring up any browned bits from bottom for about 12-15 minutes.

Tart Preparation

  • Preheat oven to 400 degrees.
  • Add ¼ cup water to caramelized onions and continue to cook, stirring, for another 2-3 minutes or until onions are soft and golden brown. Set aside to cool, discarding any extra oil in the pot.
  • Optional step: for beautiful presentation, slice shallots in wedges and brown lightly in olive oil for 3-5 minutes flipping halfway. Set aside.
  • In small saucepan over medium heat, toast nuts until fragrant, 5-7 minutes, stirring occasionally. Set aside.
  • In small bowl, whisk together heavy cream, sour cream and eggs. Add arrowroot, salt and pepper and whisk again and ensure to remove any clumps.
  • Once caramelized onions have cooled, add to cream mixture. Stir.
    Add cheese, fold in.
  • Pour mixture into prepared crust. Smooth top. Sprinkle nuts on top.
  • Bake in oven at 400 for 15 minutes. Lower temperature without opening oven door to 375. Bake until filling is just set, another 15-20 minutes, for a total of about 35 minutes or until the tart is slightly wobbly.
  • Let cool about 15 minutes before cutting. Enjoy warm and store any leftovers in airtight container.

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