Golden Onion Tart with Gruyère and Thyme

This tart is a vehicle for caramelized onions. It’s also inspired by an appetizer I ate years ago in a Swiss auberge overlooking the Lake of Geneva. It’s been so long, I can’t remember the name of the restaurant, but I do remember the onion tart. It was simple and rustic, just like the half-timbered dining room with its roaring open fire where we tasted it. Sweet, rich and minimal, this tart was perfection in its simplicity. Today I make a version of this memory while we enjoy another view from our California home. I like to serve it in small slivers with glass of wine before dinner.

Golden Onion Tart with Gruyère and Thyme
Serves 8 to 12

For the dough – adapted from a recipe by Alice Waters:
1 cup all-purpose flour
1/2 teaspoon salt
6 tablespoons unsalted butter, chilled, cut in 1/4 inch cubes
3 tablespoons ice water

Stir flour and salt together with a fork. Toss in butter. Work the butter into the flour with a fork or your fingertips until it resembles coarse meal, with some pieces of the butter apparent. Sprinkle in the water while stirring with a fork until the dough comes together, adding another tablespoon of water if necessary. Form into a ball and flatten. Wrap in plastic wrap and refrigerate 1 hour

For the filling:
2 tablespoons olive oil
2 pounds yellow onion, peeled and thinly sliced
1 teaspoon salt
2 tablespoons port wine
1 teaspoon freshly ground black pepper
2 ounces finely grated Gruyère cheese
1 teaspoon fresh thyme, plus extra for garnish
1 egg, slightly beaten

Heat olive oil over medium heat in a deep skillet or pot. Add onions and salt. Cook onions, stirring occasionally, until they are golden brown, soft and squidgy, about 30 minutes. Add port wine and cook, stirring, 2 minutes. Remove onions from heat and stir in the pepper. Cool slightly.
While the onions are cooling, roll out the dough to fit in the bottom and up the side of a 10 inch round tart tin. Sprinkle half of the cheese over the bottom of the tart. Spoon onions into the shell and spread evenly. Sprinkle 1 teaspoon thyme over the onions. Brush the exposed crust rim with the egg wash. Sprinkle the tart and crust with the remaining cheese.
Bake in a preheated 375 F. oven until the crust is firm and golden and the onions have turned a rich golden brown, without blackening, about 30 minutes. Remove and cool slightly. Serve slightly warm or at room temperature garnished with thyme sprigs.

17 thoughts on “Golden Onion Tart with Gruyère and Thyme

  1. Very beautiful tart, I love caramelized onions. It almost reminded me of a flamenkuche (not sure of the spelling), that I used to enjoy at a simple restaurant in Paris.

  2. This looks amazing- I am definitly going to try it out. I don’t think I can get Gruyère cheese here in Spain, could you recommend an alternative?

  3. Gorgeous! I love caramelized onions so much. And this doesn’t seem as terribly butter-laden as so many tarts are. 🙂

  4. This looks absolutely beautiful! I am a sucker for caramelized onions in any form, and in this tart they seem to be the star of the show! I’m bookmarking this to give it a try sometime soon.

  5. I love the delicate nature of this tart. So often people make tarts that are just too much, thick with cheese and fillings. This would be just perfect as a pre-meal treat with a chilled glass of bubbly. – S

  6. Yum! Nigella Lawson’s Domestic Goddess… cookbook has a similar recipe which I adore. Will have to give this a spin!

  7. Love this one! It’s so perfect any time of year – but I’m adding this to my list of “must make”s. I’d love to try this with blue cheese too. Just a lot less, since the flavor goes a longer way than with gruyere.

  8. Hi, this looks exactly like what was served to us in a little hamlet in Alsace, France in 2009. I have recently been given a recipe for Onion Pie from Alsace but it was much different. I am going to try your recipe very soon! Thank you so much for sharing!

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