Ingredients:

  • 1 ½ cups All-Purpose Flour (Plus extra for dusting)
  • 8 Tbsp Unsalted Butter, very cold, cut into ½ inch cubes
  • ½ tsp Salt (fine grain)
  • 1 Large Egg Yolk
  • 3–4 Tbsp Ice Water
  • 3 large Yellow Onions, sliced thinly and evenly
  • 2 Tbsp Olive Oil
  • 1 tsp Brown Sugar (optional, or Balsamic Glaze)
  • 1 Tbsp Fresh Thyme Leaves, stripped from stems
  • Salt and Black Pepper, To taste
  • 7 oz Soft Goat Cheese Log, crumbled
  • 2 Large Eggs, lightly whisked
  • ½ cup Heavy Cream (Double Cream)
  • Pinch of Nutmeg, freshly grated

Instructions:

  1. Combine Dry Ingredients: Pulse the flour and salt in a food processor (or use your fingers in a bowl).
  2. Cut in the Butter: Add the cold butter cubes. Pulse until the mixture resembles coarse sand or small peas, keeping the process quick to maintain cold temperature.
  3. Bind the Dough: Add the egg yolk and drizzle in the ice water, 1 tablespoon at a time, pulsing until the dough just comes together. Form the dough into a flat disc, wrap tightly in cling film, and chill in the refrigerator for at least 30 minutes.
  4. Sweat Onions: Heat the olive oil over medium-low heat in a heavy pan. Add the sliced onions and a generous pinch of salt. Cook, stirring occasionally, until they soften and become translucent (about 15 minutes).
  5. Caramelize: Reduce the heat to low. Continue cooking, stirring every 5–10 minutes, for 25–30 minutes more, until the onions are deep golden brown and sticky. Add brown sugar/balsamic if using. Stir in the fresh thyme leaves. Remove from heat and allow the filling to cool completely.
  6. Roll and Fit Pastry: On a lightly floured surface, roll the chilled dough into a 12-inch (30 cm) circle. Carefully drape the dough over a 9-inch tart tin with a removable bottom and gently press it into the bottom and sides. Trim the excess pastry and prick the base all over with a fork.
  7. Blind Bake: Freeze the lined tin for 15 minutes to prevent shrinkage. Preheat oven to 400°F (200°C). Line the chilled shell with parchment paper, fill with baking weights, and bake for 15 minutes. Carefully remove weights and parchment, return the shell to the oven, and bake for another 5 minutes, or until the base is dry and lightly golden. Reduce the oven temperature to 350°F (175°C).
  8. Prepare Custard: Whisk the eggs, heavy cream, salt, pepper, and nutmeg until well combined.
  9. Layer and Pour: Scatter half of the crumbled goat cheese over the base of the blind-baked shell. Spread the cooled caramelized onions evenly over the cheese. Pour the egg custard mixture gently over the filling. Sprinkle the remaining goat cheese on top.
  10. Final Bake: Bake in the preheated 350°F (175°C) oven for 25–30 minutes, or until the custard is set and the top is golden brown.
  11. Cool and Serve: Allow the tart to rest on a wire rack for at least 15 minutes before attempting to slice. Serve warm or cold.