Savory Onion Tart Delight (Printable Version)

Golden, buttery tart layered with sweet caramelized onions and creamy custard, perfect for light meals.

# What You'll Need:

→ Pastry

01 - 1 1/4 cups all-purpose flour
02 - 1/2 teaspoon salt
03 - 1/2 cup cold unsalted butter, cubed
04 - 3 to 4 tablespoons ice water

→ Onion Filling

05 - 2 tablespoons olive oil
06 - 2 tablespoons unsalted butter
07 - 4 large yellow onions, thinly sliced
08 - 1 teaspoon sugar
09 - 1/2 teaspoon salt
10 - 1/4 teaspoon black pepper
11 - 1/4 teaspoon dried thyme or 1 teaspoon fresh thyme leaves
12 - 2 cloves garlic, minced

→ Custard

13 - 3 large eggs
14 - 3/4 cup heavy cream
15 - 1/2 cup whole milk
16 - 1/2 teaspoon salt
17 - 1/4 teaspoon ground nutmeg
18 - 1/2 cup grated Gruyère cheese

# Directions:

01 - Set oven to 375°F to prepare for baking.
02 - Combine flour and salt in a large bowl. Cut in butter until mixture forms coarse crumbs. Add ice water tablespoon by tablespoon, mixing until dough forms. Shape into a disc, wrap, and refrigerate for 20 minutes.
03 - Roll dough on floured surface to fit a 9-inch tart pan. Press into pan, trim edges, prick base with fork. Refrigerate for 10 minutes.
04 - Line tart shell with parchment and fill with pie weights. Bake 15 minutes, remove weights and parchment, then bake an additional 5 minutes. Allow to cool slightly.
05 - Heat olive oil and butter on medium in a skillet. Add onions, salt, pepper, thyme, and sugar. Cook, stirring occasionally, until soft and golden, about 25 to 30 minutes. Stir in garlic and cook 2 minutes more. Let cool.
06 - Whisk eggs, heavy cream, whole milk, salt, and nutmeg until combined.
07 - Evenly spread caramelized onions over crust. Sprinkle with Gruyère cheese. Pour custard mixture on top.
08 - Bake for 25 to 30 minutes until custard is set and golden. Let rest 10 minutes before slicing.

# Expert Advice:

01 -
  • The onions turn sweet and jammy as they cook, filling your kitchen with the kind of smell that makes people wander in asking whats for dinner.
  • It looks fancy enough for guests but comes together with ingredients you probably already have.
  • You can serve it warm, cold, or at room temperature, which means less stress and more flexibility.
  • The crisp pastry and creamy custard create a texture contrast that keeps every bite interesting.
02 -
  • Don't skip chilling the pastry or it will shrink dramatically in the oven and you'll be left with a sad, shallow shell.
  • Caramelizing onions takes patience; if you try to rush it over high heat, they'll burn on the edges and stay raw in the middle.
  • Let the tart cool for at least 10 minutes before slicing or the custard will run everywhere and you'll lose that clean, beautiful wedge.
03 -
  • If your dough feels too crumbly, add water a teaspoon at a time; if it's sticky, dust it lightly with flour and chill it longer.
  • Use a mandoline to slice the onions evenly so they cook at the same rate and caramelize perfectly.
  • Let the custard mixture sit for a minute before pouring so any bubbles rise to the top, giving you a smoother finish.

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