1. Grease a loaf tin, 150mm x 90mm x 70mm in size, with vegetable oil spray, then line it with baking paper.
2. Heat the oven to 150°C, fan forced.
3. Scatter the hazelnuts over a lined baking tray and place into the preheated oven for 15-20 minutes, until evenly roasted. Allow to cool completely at room temperature.
4. Place the milk chocolate and white chocolate into a saucepan and gently melt over an induction cooktop on setting 4.
5. Add the hazelnut spread and mix with a spatula until combined and smooth. Allow to cool at room temperature.
6. Once the mixture is lukewarm, add the cooled hazelnuts, then pour the mixture into the prepared loaf tin.
7. Smooth the mixture to create a flat surface as this will become the base of the torrone.
8. Allow to set at room temperature overnight, or in the refrigerator for 20-30 minutes, before removing from the tin.
9. Turn the torrone over and dust the surface with cocoa powder.

Note:    Serve at room temperature. Store in an airtight container at room temperature for up to 10 days.