Step 1

Grease the base and sides of a 5cm-deep, 20cm x 30cm lamington pan. Line with baking paper, leaving some overhanging.

Step 2

Place shortbread in a food processor and whiz to fine crumbs. Add the butter, coconut and a pinch of salt, and pulse to combine. Press into the base of the prepared pan, using the back of a spoon to smooth the surface.

Step 3

Spread over gelato, then dulce de leche. Smooth the surface, then freeze for 1 hour to firm up.

Step 4

Place chocolate in a heatproof bowl. Place cream in a pan over medium heat and bring to just below boiling point. Pour the hot cream over the chocolate and stir until melted and smooth. In 2 batches, stir in the oil until combined.

Step 5

Cool slightly, then pour over the slice and smooth the surface. Freeze overnight or until firm.

Step 6

Remove from freezer 20 minutes before serving. Using a warm knife, cut into pieces and serve immediately.