
A sophisticated savory tart featuring deeply caramelized onions and sharp mature cheddar encased in a buttery, flaky homemade crust. This rich and comforting dish is perfect for a weekend brunch, a vegetarian main course, or a refined afternoon tea.
To make the pastry, combine the flour and cold cubed butter in a large bowl. Rub the mixture together with your fingertips until it resembles coarse breadcrumbs. Add the beaten egg and mix with your hands until the dough just comes together. Shape into a disc, wrap in plastic, and chill for at least 30 minutes (or freeze for up to a month).
On a lightly floured surface, roll the pastry out into a circle roughly 28cm in diameter. Carefully lift the pastry using a rolling pin and drape it over a 23cm tart tin. Use a small ball of pastry scraps to gently press the dough into the base and up the sides, allowing the excess to overhang. Chill in the fridge for another 20 minutes.
While the pastry chills, melt 50g of butter in a pan over low-medium heat. Add the sliced onions and cook for about 45 minutes, stirring occasionally, until they are golden, sticky, and caramelized. Season generously with salt, stir in the double cream and nutmeg, and bring to a gentle simmer before removing from the heat.
Preheat your oven to 200°C (180°C fan/gas 6). Lightly prick the base of the chilled tart shell with a fork. Line with baking parchment and fill with baking beans or rice. Blind bake for 20 minutes, then remove the beans and parchment and bake for an additional 10-15 minutes until the pastry is light brown and cooked through.
Stir the egg yolks and two-thirds of the grated cheese into the onion and cream mixture. Pour the filling into the pre-baked pastry case and sprinkle the remaining cheese on top. Bake for 20-25 minutes until the filling is just set and golden. Let the tart cool completely in the tin, then trim the overhanging pastry with a serrated knife for a clean edge. Garnish with fresh chives before serving.
For the flakiest pastry, ensure your butter and egg are very cold before starting. Don't rush the onions; the slow caramelization process is essential for developing their natural sweetness. Trimming the pastry overhang after the final bake ensures a perfectly neat, professional-looking edge that hasn't shrunk during cooking.




