Preparation:

1: Make the Base

1. Line a 20 cm x 20 cm baking tin with baking paper, allowing overhang on the sides for easy lifting later.
2. In a large bowl, combine the graham cracker/digestive crumbs, melted butter, sweetened condensed milk, and shredded coconut if using.
3. Mix until the texture resembles a sticky, damp sand.
4. Press the mixture firmly and evenly into the base of the tin using the back of a spoon or your fingers.
5. Place the tin in the refrigerator to chill while preparing the caramel layer.

2: Make the Caramel Layer

1. In a medium saucepan, combine the butter, brown sugar, sweetened condensed milk, golden syrup, and a pinch of salt.
2. Cook over medium-low heat, stirring constantly with a wooden spoon or silicone spatula.
3. After 6–8 minutes, the mixture will begin to thicken and bubble—keep stirring until it’s smooth, golden, and slightly pulling away from the sides.
4. Remove from heat and pour the hot caramel mixture over the chilled biscuit base.
5. Smooth with a spatula and refrigerate for at least 1 hour, or until set.

3: Make the Chocolate Topping

1. In a heatproof bowl, combine the chocolate chips and oil.
2. Microwave in 30-second intervals, stirring between each, until fully melted and smooth. Alternatively, melt over a saucepan of simmering water (double boiler method).
3. Pour the chocolate mixture evenly over the chilled caramel layer.
4. Gently tilt the tin or use an offset spatula to spread the chocolate evenly across the top.
5. Chill for at least 1 more hour or until chocolate is firm and set.

4: Slice and Serve

1. Once fully chilled, remove the slice from the tin using the baking paper.
2. Use a sharp knife warmed in hot water (and dried) to cut clean squares.
3. Wipe the knife between cuts for smooth edges.
4. Serve chilled or at room temperature.