• Line a 20cm (8in) square baking tray with greaseproof paper.

Biscuit Layer

• Blitz the biscuits in a food processor to a fine crumb. Mix through the chopped hazelnuts and add the melted butter.
• Press the biscuit into an even layer across the bottom of your lined tin.

Caramel Layer

• In a large saucepan, add all your caramel ingredients and heat over a medium heat until the butter and sugar are completely melted. Keep stirring to ensure nothing catches on the bottom!
• Allow the mixture to boil for around 5 minutes, stirring constantly.
• Your caramel will be ready when it has changed to a slightly darker golden colour. Colour of straw.
• Pour the caramel over the biscuit base and leave it to set for an hour. This can be done on the side or in the fridge. You want it to be set before pouring your chocolate over, so that you get those distinct lines.

Chocolate Layer

• Final stage. Melt your chocolate carefully in the microwave in short bursts with lots of stirring, or using a bain-marie.
• Add your Nutella into your melted chocolate. And heat again briefly, so that the spread melts. Mix thoroughly. Stir through the chopped hazelnuts.
• Pour over your set caramel. I bang my pan a couple of times on a work surface to make sure there are no trapped air bubbles.
• Roughly chop the Ferrero Rocher and sprinkle over the top, if using.
• Allow to set completely before slicing and enjoying. I leave mine overnight.