Tarte aux Oignons
A classic rustic tart from northeastern France: a crispy shortcrust pastry base loaded with a mountain of yellow onions slow-caramelized in butter, all enveloped in a velvety egg custard with a hint of nutmeg.
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70 min
Easy
Francesa (Alsaciana)
6 servings
The story behind
You seriously have absolutely no idea what an incredible, deeply rewarding and comforting flavor experience this simple tart delivers—it is the ultimate definition of how patience can turn a humble veggie into pure culinary gold! The very first time I experienced an authentic *Tarte aux Oignons* was during a chilly autumn drive through the gorgeous wine villages of Alsace. It completely blew my mind to discover how magnificent sweet onions become when sweated slow and low with nothing but pure butter. The ultimate golden rule shared by a local baker to failure-proof this recipe is cooking the onions with absolute calm (never rushing to brown them harshly) so they bleed out their natural sugars, and blind-baking the pastry crust first to ensure it stays ultra-crispy and supports the heavy custard matrix without getting soggy. Personally, I love putting this menu together for weekend brunches because it tastes exceptional whether served warm or at room temperature. It looks identical to the photo layout when you bake it inside a classic round aluminum pan, letting the top custard brown into a glossy, mottled golden surface, and place a blue-and-white checkered kitchen towel casually on the side to give it that stunning rustic farmhouse aesthetic, exactly like the setup in Tarte aux Oignons.jpg. Pair with a chilled glass of local dry white wine like a Riesling for a flawless pairing. You will fall in love with it completely!
Instructions
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1Preheat your oven to 190°C (375°F) and lightly grease a standard 26-cm round aluminum tart pan with butter.
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2Fit your rolled shortcrust pastry smoothly into the pan, pressing gently into the bottom and inner wall corners. Prick the entire base with a fork and chill in the refrigerator for 15 minutes to cold-stabilize the butter fats.
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3Blind-bake the crust (line with parchment paper and fill with baking weights or dried beans) at 190°C for 12 minutes. Remove weights and parchment, and bake for an additional 3 minutes until firm and dry to the eye. Set aside.
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4While the crust par-bakes, melt the 3 tablespoons of butter in a large skillet over low heat.
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5Tumble the massive mountain of sliced onions into the skillet with a healthy pinch of salt. Cook slowly for 20 to 25 minutes, stirring frequently, until the onions are completely melted, translucent, and sweet-golden, ensuring they do not scorch.
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6In a medium mixing bowl, whisk together the 3 eggs, heavy cream, a pinch of ground nutmeg, sea salt, and cracked black pepper to preference until a uniform emulsion is formed.
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7Fold the warm caramelized onions directly into the bowl with the egg and cream mixture, stirring gently to distribute evenly.
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8Pour the whole onion custard fill into the par-baked pastry shell, smoothing the top surface out so the onion strands lay flat and level.
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9Bake at 190°C for 25 to 30 minutes until the center sets structurally to the touch and the top layer develops that gorgeous, shiny, mottled golden-yellow coat matching Tarte aux Oignons.jpg down to every rustic detail. Let rest for 10 minutes before slicing.
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