French onion tart

Prep 20 min
Total 2 hours 5 min
Plus chilling time
Serves 8



2 cups
all-purpose flour
1/2 tsp
3/4 cup
cold unsalted butter, cubed
1 tsp
white vinegar


1 tbsp
vegetable oil
red onion, sliced
shallots, peeled and sliced
1/2 tsp
1/2 tsp
granulated sugar
1/2 cup
35% cream
1/4 cup
2 cups
grated gruyère
1 tsp
fresh thyme leaves


  • WHIRL flour with salt in a food processor. Add butter and pulse until coarse crumbs form. Gradually add 1/4 cup ice water and vinegar, pulsing after each addition. Pulse just until dough starts to come together. Gather into a ball, then press into a disc. Wrap in plastic wrap. Refrigerate at least 45 min or up to 3 days.
  • HEAT a large non-stick frying pan over medium. Add oil, then onions and shallots. Cook, without stirring, for 5 min. Reduce heat to medium-low. Add salt and sugar. Season with pepper. Cook, stirring often, until onions turn deep brown, 6 to 12 more min. Set aside.
  • WHISK eggs with cream and milk in a medium bowl until smooth. Set aside.
  • PREHEAT oven to 400F. Lay an 11-in. fluted tart pan on a baking sheet. Cut out a foot-long piece of parchment paper. Roll dough on a lightly floured surface into a 13-in. circle, about 1/4 in. thick. Carefully lift dough into tart pan. Gently press dough into the corners and up the edges of the pan. Trim and discard excess. Prick the dough with a fork about 15 times. Lay parchment on the shell and fill with 2 cups dry beans or pie weights.
  • BAKE in centre of oven for 15 min, then cover with foil. Continue baking until shell is just golden, about 15 more min. Remove to a rack. Reduce heat to 350F. Lift out parchment and beans. Reserve beans for future use.
  • SPRINKLE half of cheese, then onion mixture over warm crust. Add egg mixture. Sprinkle with remaining cheese, then thyme.
  • BAKE in centre of oven until top is firm, 20 to 22 min. Transfer to a rack.Let tart rest 10 min before serving.


Calories 382, Protein 10 g, Carbohydrates 26 g, Fat 27 g, Fibre 2 g, Sodium 431 mg.

Prep Tip

Pre-baking a tart shell or “blind baking” with dry beans or pie weights helps prevent the crust from shrinking or puffing up while baking.

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