Sticky Toffee Treacle Tart

STEP 1: MAKE THE ICE CREAM BASE

Heat the milk, cream, vanilla seeds and pod until just below a simmer, then take off the heat and leave to infuse for 15 minutes. Whisk the egg yolks, sugar and salt together, then whisk in the warm milk a little at a time. Return to the pan and cook over low heat, stirring constantly, to 175–180°F (80–82°C), until the custard coats the back of a spoon. Strain, cool over an ice bath and chill for at least 4 hours, or overnight.

STEP 2: MAKE THE GOLDEN SYRUP

Heat the 1/4 cup (50 g) sugar with the 1 tbsp water in the medium saucepan, swirling, to a deep amber caramel. Off the heat, carefully pour in the boiling water; it will spit. Return to low heat and stir until smooth, then add the 2 cups (400 g) sugar and the lemon slices and stir until dissolved. Stop stirring and simmer very gently for 35–45 minutes, to 225–230°F (107–110°C), until golden. Lift out the lemon. Weigh out 300 g for the filling; any extra keeps in a sealed jar.

STEP 3: MAKE AND CHILL THE PASTRY

Rub the butter into the flour, powdered sugar, salt and vanilla seeds until the mixture looks like fine crumbs. Add the egg yolk and just enough ice-cold water to bring it together. Flatten to a disc, wrap and chill for 30 minutes. Roll to about 1/8 in (3 mm), line the tart tin, prick the base and chill for 20 minutes. Reroll the trimmings, cut 8–10 lightning bolts plus a few spares, and chill them on the lined baking tray.

STEP 4: BLIND BAKE AND SEAL THE CASE

Preheat the oven to 400°F (200°C) with the heavy baking sheet inside. Line the pastry case with parchment and baking beans and bake for 15 minutes. Remove the paper and beans and bake for 8–10 minutes more, until dry and pale golden. Brush the inside with the beaten egg white and return to the oven for 1 minute to seal. Trim the edge, then lower the oven to 300°F (150°C).

STEP 5: MAKE THE FILLING

Blend the dates with the warm orange juice to a smooth purée. Warm the golden syrup and black treacle together until fluid, then stir in the date purée, orange zest, breadcrumbs, salt, cream and egg until evenly combined.

STEP 6: BAKE THE TART AND LIGHTNING BOLTS

Pour the filling into the case and level it. Bake on the hot baking sheet at 300°F (150°C) for 40 minutes, until just set with a slight wobble in the center. Meanwhile, brush the lightning bolts with egg wash and bake them on their own tray on a lower shelf for 12–15 minutes, checking from 10 minutes, until golden; they are thin and burn fast, so bake the spares too. Cool the bolts on the tray.

STEP 7: CHURN THE ICE CREAM

While the tart bakes, churn the chilled custard in the ice cream machine following the manufacturer's instructions. Transfer to a container and freeze for 1–2 hours, until firm enough to scoop.

STEP 8: COOL AND DEMOLD

Cool the tart in the tin for at least 30 minutes, then demold onto a serving plate.

STEP 9: MAKE THE SAUCE AND SERVE

Melt the butter, dark brown sugar and black treacle together in the small saucepan. Add the cream and salt and bubble for 3–4 minutes until glossy. Arrange the lightning bolts on the tart. Serve slices just warm with a neat scoop of vanilla ice cream and the sticky toffee sauce alongside.