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Alsatian Onion Tart

Scott Phillips

Servings: four for supper, eight as a starter.

This classic French regional tart of good Gruyère and “melted” onions, bound with a savory custard, is one of my favorites. For an interesting variation, brush the prebaked tart shell with a thin layer of Dijon mustard, or add 1 Tbs. of finely minced tarragon to the custard. Be sure to buy the best quality Gruyère.


  • 2 Tbs. vegetable oil
  • 2 Tbs. unsalted butter
  • 4 medium onions, cut in half and very thinly sliced
  • A sprinkling of granulated sugar
  • Kosher salt and freshly ground black pepper
  • 3 large eggs
  • 1-1/4 cups heavy cream
  • A tiny pinch nutmeg (preferably freshly grated)
  • 1/3 cup (about 1-1/4 oz.) finely grated Gruyère
  • 1 partially baked tart shell in a 10-inch porcelain quiche pan or a 10-1/2- or 11-inch metal tart pan 

Nutritional Information

  • Calories (kcal) : 450
  • Fat Calories (kcal): 330
  • Fat (g): 37
  • Saturated Fat (g): 20
  • Polyunsaturated Fat (g): 3
  • Monounsaturated Fat (g): 11
  • Cholesterol (mg): 180
  • Sodium (mg): 450
  • Carbohydrates (g): 23
  • Fiber (g): 1
  • Protein (g): 8


  • Heat the oil and butter in a cast-iron or other heavy-based 10-  to 12-inch skillet. Add the onions and sugar, season with salt and pepper, and sauté over medium-high heat, stirring frequently, until lightly browned. Lower the heat and continue to cook the onions until very soft and evenly browned, stirring frequently, another 30 to 40 minutes; you may need to add a little more oil. When the onions are done, transfer them to a strainer and drain.
  • Heat the oven to 375°F. If using a tart pan with a removable bottom, put it on a baking sheet. In a bowl, whisk the eggs and cream. Season with 3/4 tsp. salt, a scant 1/2 tsp. pepper, and the nutmeg. Add the drained onions and half of the cheese and blend thoroughly. Fill the prepared tart shell with the onions and custard. Top with the remaining cheese and bake until the tip of a knife comes out clean and the top of the tart is puffed and brown, 40 to 45 minutes. Let cool for at least 15 to 20 minutes before serving.


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Reviews (4 reviews)

  • Pumpkiesmom | 09/11/2014

    Quick and easy. A keeper.

  • saradems | 04/26/2009

    Excellent dinner and actually pretty inexpensive, too (a little pricey cheese goes a long way!). It's very rich, so I would recommending serving with a salad or another vegetable (we used broccoli from our garden). Great flavor, and the crust that the recipe links to is one of the easiest crusts I've ever made! I didn't have the right pan, so I used a 10 inch springform pan and there was no problem with that.

  • OrganicGirl98 | 03/16/2009

    I followed the recipe exactly and it was sublime. I served it at a dinner party, and was able to do a lot of the prep ahead of time (carmelized the onions and made tart crust the day before). When it was finished baking, I left it in a warm oven (160 degrees) and it set nicely and stayed warm. Will definitely make again.

  • Joy123 | 09/27/2008

    great and easy to make

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