French onion tart



20 min


2 hrs 5 min



* PLUS chilling time
French onion tart

Photo by Roberto Caruso


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


  • 1 tbsp vegetable oil
  • 1 red onion , sliced
  • 4 shallots , peeled and sliced
  • 1/2 tsp salt
  • 1/2 tsp granulated sugar
  • 4 eggs
  • 1/2 cup 35% cream
  • 1/4 cup milk
  • 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.

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.

Nutrition (per serving)

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