Make the pastry by rubbing the cold Unsalted Butter into the Plain Flour with the Icing Sugar and a pinch of Salt until the mixture resembles fine breadcrumbs.
Stir in the Egg Yolk and a little cold Water to bring the dough together, then form into a disc, wrap and chill in the fridge for at least 30 minutes.
Preheat the oven to 190°C (375°F). Roll out the chilled dough and line a 23cm tart tin, trimming the edges; chill the lined tin for 10–15 minutes to relax the pastry.
Blind-bake the pastry case: line with baking paper and baking beans (or rice), bake for 12–15 minutes until the edges are just set, remove the paper and beans and bake a further 5 minutes to dry the base.
While the case cools slightly, prepare the filling by stirring together the Golden Syrup, White Breadcrumbs, the grated Lemon Zest and a little Lemon Juice until smooth.
Beat the Eggs lightly and mix them into the syrup-breadcrumb mixture along with the Double Cream and a small pinch of Salt to balance the sweetness.
Pour the filling into the partially baked pastry case and return to the oven for 20–25 minutes, or until the filling is set but still slightly wobbly in the center.
Allow the tart to cool for a little while so the filling firms up, then serve warm or at room temperature with extra Double Cream or a scoop of vanilla ice cream.
