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Savory Onion Tart Gruyère

Featured in Snacks and Bites Everyone Loves.

Golden onions, slow-cooked with a touch of sweetness, are surrounded by rich Gruyère and fresh thyme in a custard filling. Add buttery crust baked to crisp perfection for a comforting yet polished dish you’ll love serving anytime.
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Updated on Sat, 19 Apr 2025 00:30:49 GMT
Savory Onion Tart Pin it
Savory Onion Tart | mecooking.com

Craving something fancy but homey? This Onion Tart with a French twist hits the spot. It combines paper-thin onions, melty Gruyère, and garden-fresh herbs for a tasty spin on a beloved French classic.

WHAT YOU'LL NEED

  • All-Purpose Flour: 2 cups to form your base crust.
  • Kosher Salt: ½ teaspoon to boost the crust flavor.
  • Sugar: 1 tablespoon for a hint of sweetness in your base.
  • Cold Unsalted Butter: 12 tablespoons (1 ½ sticks), cut into chunks for that perfect flaky texture.
  • Ice Water: ½ cup to pull your dough together nicely.
  • Gruyère Cheese: 1 cup, grated, giving that wonderful nutty taste.
  • Fresh Thyme: 1 ½ teaspoons, chopped small, adding woody aroma.
  • Fresh Chives: 2 teaspoons, finely chopped, for that mild oniony kick.
  • Sweet Onions: 1 ¼ lbs (roughly 3 medium), sliced thin as your star ingredient.
  • Heavy Cream: 1 tablespoon to coat your onions before they go in the oven.
  • Unsalted Butter: 3 tablespoons, in small chunks, to make everything extra tasty.
  • Kosher Salt: 1 teaspoon to bring out all those lovely flavors.

HOW TO MAKE IT

Step 1:
Mix flour, kosher salt and sugar in your food processor or a big bowl. Throw in the cold butter chunks and pulse until you've got something that looks like breadcrumbs.
Step 2:
Slowly add your ice-cold water while mixing until everything sticks together. Wrap it up in plastic and stick it in the fridge for at least half an hour or freeze it for later.
Step 3:
Take your sweet onions, peel them, cut them in half and slice them thinly into half-moon shapes. Try to keep them intact.
Step 4:
Get your dough and roll it out to a 10 x 14 inch rectangle. Put it on a baking sheet lined with parchment paper.
Step 5:
Place your onion half-moons diagonally across the dough, slightly overlapping each other. Scatter Gruyère cheese all over, even to the edges, then sprinkle with your chopped thyme and chives.
Step 6:
Grab your cream and lightly brush the onions. Drop the diced butter on top and finish with a sprinkle of kosher salt.
Step 7:
Pop it in a 400°F (200°C) oven for about 40 minutes until everything turns golden brown and your onions are soft. If the edges get too dark, cover them with foil.
Step 8:
Let it cool a bit before cutting into pieces. You can eat it warm or at room temp.

Fresh Ideas for Serving and Keeping

  • Enjoy this tart either slightly warm or cool, cut however you like.
  • Try it with a simple green salad or sip some white wine alongside for a true French meal vibe.
  • Pop leftovers in the fridge in a sealed container and they'll stay good up to 3 days.
  • To get back that crispy texture, warm it up at 350°F for 10-12 minutes.

Expert Chef Advice

  • Julia Child always said the secret's in getting that dough super cold before you roll it out for the flakiest results.
  • According to Ina Garten, don't skimp on your butter quality if you want amazing crust texture and taste.
  • Gordon Ramsay loves adding a splash of balsamic when cooking onions to bring out their natural sweetness.

MIX IT UP

  • Throw in some cooked mushrooms or browned leeks for extra depth and earthy notes.
  • Want something heartier? Sprinkle some crispy bacon bits or pancetta through the onion mixture.
  • Short on time? A ready-made puff pastry base works wonders for a lighter result.

Savory Onion Tart

Caramelized onions and Gruyère cheese baked with herbs in a flaky crust. This flavorful dish is light, rustic, and so easy to pair with meals.

Prep Time
40 Minutes
Cook Time
40 Minutes
Total Time
80 Minutes
By: Mariana


Difficulty: Intermediate

Cuisine: French

Yield: 1 tart

Dietary: Vegetarian

Ingredients

01 ½ cup ice-cold water.
02 2 teaspoons minced fresh chives.
03 12 tablespoons chilled unsalted butter, cut into small cubes (1 ½ sticks).
04 1 ½ teaspoons minced thyme leaves.
05 1 tablespoon granulated sugar.
06 ½ teaspoon salt, kosher-style.
07 2 cups plain white flour.
08 3 medium-sized sweet onions (about 1 ¼ lbs), sliced thinly.
09 1 tablespoon of cream, heavy variety.
10 1 cup shredded Gruyère cheese (4 oz).
11 3 tablespoons butter, unsalted, cut into little pieces.
12 1 teaspoon kosher-style salt for sprinkling.

Instructions

Step 01

Throw the flour, sugar, and kosher salt into a bowl or food processor and mix it up.

Step 02

Toss the diced butter in and mix until it's crumbly, like damp sand.

Step 03

Pour the ice water in a little at a time, stirring or processing just until everything sticks together.

Step 04

Wrap the dough tightly in plastic and pop it in the fridge for at least half an hour. Or freeze it for later.

Step 05

Carefully peel and slice your onions into super-thin half-moons. Try not to break them up.

Step 06

Roll out the dough into a big rectangle (10 x 14 inches) and set it on parchment paper on a baking sheet. Lay the onion slices on top in neat, slightly overlapping rows.

Step 07

Scatter Gruyère cheese all over, making sure it gets to the edges. Sprinkle the thyme and chives on top.

Step 08

Lightly brush the sliced onions with the heavy cream.

Step 09

Spread small dots of diced butter over the surface of the onions.

Step 10

Sprinkle some kosher salt evenly across the top.

Step 11

Pop the tart into an oven preheated to 400°F (200°C) and bake for about 40 minutes. It should come out golden brown with fully cooked onions.

Step 12

If the pastry edges start over-browning, loosely cover them with foil partway through baking.

Step 13

Let it cool down a little, then slice it into strips, squares, or wedges. Enjoy warm or at room temp.

Notes

  1. Give the onions a deeper flavor by caramelizing them before placing them on the pastry.
  2. Great served with a salad on the side for balance.

Nutrition Facts (Per Serving)

It is important to consider this information as approximate and not to use it as definitive health advice.
  • Calories: 350
  • Total Fat: 22 g
  • Total Carbohydrate: 30 g
  • Protein: 8 g