Apple Crumble Treacle Tart

STEP 1: MAKE THE ICE CREAM BASE AND TOAST THE PECANS

Melt the butter in a light-colored pan over medium heat and cook, swirling, until the milk solids turn hazelnut-brown and smell nutty, 5–7 minutes. Pour into a bowl, scraping in the brown bits. Heat the milk and cream until just simmering at the edges. Whisk the egg yolks with the light brown sugar and 1/2 tsp of the flaky sea salt, gradually whisk in the hot milk, then return to the pan and cook, stirring, to 175–180°F (80–82°C), until the custard coats the spoon. Off the heat, blend in the brown butter and vanilla extract with a stick blender. Strain, cool over ice, then chill for at least 4 hours or overnight. The base is deliberately low in sugar so it balances the rich tart. Meanwhile, toast the pecans in a dry skillet over medium heat for 4–5 minutes until fragrant, toss with the remaining 1/4 tsp salt, cool and chop roughly.

STEP 2: MAKE THE GOLDEN SYRUP

In a heavy saucepan, heat the 1/4 cup (50 g) sugar with the 1 tbsp water, swirling rather than stirring, until it becomes a deep amber caramel. Take the pan off the heat and 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. Stir until the sugar dissolves, then stop stirring and simmer very gently, uncovered, for 35–45 minutes, until the syrup is golden and reaches 225–230°F (107–110°C) on a digital thermometer. Lift out the lemon slices and let cool. The syrup thickens as it cools; weigh out 380 g for the filling and store any extra in a clean jar.

STEP 3: MAKE AND CHILL THE PASTRY

Combine the flour, powdered sugar and salt, then rub in the cold butter until the mixture resembles fine crumbs. Add the egg yolk (keep the white for sealing the case) and just enough ice-cold water to bring the dough together. Flatten to a disc, wrap and chill for 30 minutes. Roll out on a lightly floured surface to 1/8–3/16 in (4 mm) thick — noticeably thicker than a very thin case — and line the tart tin, leaving a little overhang. Prick the base and chill for 20 minutes more.

STEP 4: DRY THE APPLE SLICES

Start this while the pastry chills. Heat the oven to 200°F (95°C). Stir the lemon juice into the cold water. Slice the Pink Lady apple paper-thin through the core, dipping each slice into the lemon water as you go. Pat dry, lay on a parchment-lined baking sheet, dust lightly with the powdered sugar and dry for 1–1 1/2 hours, turning once, until leathery-crisp. A dehydrator at 135°F (57°C) works too and frees the oven. Set aside.

STEP 5: BLIND BAKE TO DEEP GOLDEN

Raise the oven to 400°F (200°C) with a heavy baking sheet on the lowest shelf. Line the chilled case with parchment and baking beans and bake on the hot sheet for 15 minutes. Remove the paper and beans and bake 10–12 minutes more, until the base is dry and golden, not pale. Brush the inside with the reserved egg white and return to the oven for 2 minutes to seal. Trim the overhang. Reduce the oven to 350°F (180°C). The case should already be golden before any filling goes in.

STEP 6: COOK THE COMPOTE DRY

Melt the butter in a skillet, add the diced Pink Lady and Granny Smith apples, the light brown sugar and the cinnamon, and cook over medium heat for 6–8 minutes, until the apples are tender but hold their shape and the pan is nearly dry. Spread on a plate to cool completely, and drain off any juice that collects before using.

STEP 7: PRE-BAKE THE CRUMBLE

Combine the flour, rolled oats, demerara sugar and salt, then rub in the cold butter until the mixture forms rough clumps. Scatter on a parchment-lined baking sheet and bake at 350°F (180°C) for 12–15 minutes until golden. Let cool.

STEP 8: FILL AND BAKE

Warm the 380 g golden syrup until pourable, then stir in the breadcrumbs, lemon zest and juice, salt, cream and beaten egg. Spread the cooled compote evenly over the sealed case, then pour the syrup filling over it. Bake on the hot sheet on the lowest shelf at 350°F (180°C) for 30 minutes. Scatter the crumble over the top and bake 10–15 minutes more, until the filling is just set with a slight wobble and the pastry rim is deep golden brown.

STEP 9: CHURN, FINISH AND SERVE

Churn the chilled ice cream base in an ice cream machine, adding the chopped pecans in the last minute, then firm up in the freezer for 1–2 hours. Cool the tart in the tin for at least 30 minutes so the filling sets, then unmold. Just before serving, arrange the dried apple slices over the crumble. Serve the tart just warm with a scoop of the ice cream.