A crisp pastry case under a creamy filling of slow-caramelized onion and melted cheese. Simple ingredients, serious flavour — lovely warm or at room temperature.
Ingredients
1 sheet of shortcrust pastry; 3 medium onions; 200 g grated cheese (Emmental, mozzarella, or Gruyère); 3 eggs; 200 ml cooking cream; 2 tbsp extra virgin olive oil; 1 tbsp butter; salt and black pepper to taste; a pinch of thyme or nutmeg (optional).
Method
Heat the oven to 180°C. Line a tart tin with the pastry, fitting it well into the base and edges, and prick the base with a fork. Slice the onions finely and cook them slowly in the olive oil and butter with a pinch of salt over medium-low heat for 20–25 minutes, stirring now and then, until soft, golden, and lightly caramelized. Whisk the eggs with the cream, black pepper, and the thyme or nutmeg if using, then stir in the grated cheese. Spread the cooked onion over the pastry and pour the egg and cheese mixture evenly over the top. Bake for 30–40 minutes, until the filling is set and the top is a beautiful golden colour; cover the edges with foil if the pastry browns too fast. Rest the tart for about 10 minutes before slicing so the portions hold together, and serve warm or at room temperature.
Tips
Caramelize the onion slowly — it turns sweet and deep without any added sugar; blending Gruyère with mozzarella or Emmental gives the tastiest, meltiest filling; blind bake the pastry for 10 minutes first if you want an extra crisp base; sautéed mushrooms, bacon, ham, or spinach all make great variations; serve with a green salad, fresh tomatoes, or roast vegetables.
