Nutty Caramel and Chocolate Slice

¼ cup unsweetened cocoa powder
½ cup firmly packed brown sugar
1 large egg, beaten slightly
½ teaspoon vanilla
¼ cup plain flour
Pinch of salt

Caramel topping

90g unsalted butter
3 tablespoons Golden Syrup
1 ½ cups firmly packed brown sugar
½ cup cream
150g toasted pecans
170g toasted walnuts
1 teaspoon vanilla
Optional: 2 teaspoons dark run

• Preheat oven to 180°C (356°F).
• Line the bottom of a 32x24cm slice or baking tin with baking paper. Use the tin as a guide to cut out the paper. Butter the baking paper slightly. Set the baking tin aside.
• Place butter and cocoa in a heavy-based saucepan over medium heat. Stir until butter melts and mixture is smooth. Remove from heat, whisk in the sugar, egg and vanilla then srit in the flour and salt. Scrape mixture into the prepared tin and tilt the tin to coat the base evenly.
• Bake base for about 10 minutes or until just firm and slightly pulling away from the sides of the tin. Cool the base in its tin on a wire rack.
• For the topping, melt the butter in a heavy-based saucepan over medium heat. Add the golden syrup and sugar and bring to the boil, stirring. Attach a warmed sugar thermometer to the side of the saucepan. Note: warm the sugar thermometer in hot water before attaching it to the pan to prevent it bursting on contact with the hot caramel. Stir the boiling topping mixture occasionally until it registers 122°C (252°F) or hard-ball stage on the thermometer. Remove saucepan from heat and carefully stir in the cream and nuts. Return saucepan to heat and boil until the mixture reaches 116°C (241°F) or soft-ball stage on the thermometer, stirring occasionally - this only take a few minutes. Remove from heat, cool for a minute then add vanilla and optional rum.
• Pour the caramel/nut mixture over the base and spread it evenly with a wooden spoon. Allow the slice to cool in the tin on a wire rack. When cool, wrap it tightly and refrigerate it in the tin until cold and firm for at least 2 hours.
• Carefully turn the slice out of the tin, peel off the paper, turn it nut-side up and slice it into thin strips. Layer the strips in an airtight container separated by sheets of waxed paper. Cover tightly and store, refigerated, for up to 1 week. Makes about 30 slices.