Line a 20cm x 20cm rectangle tin with baking paper.
Crush the biscuits in the food processor and combine with the pulverised roasted hazelnuts.
Melt the 120g of butter in the microwave or in a small saucepan over low heat.
Add the melted butter to the biscuit and hazelnut mixture and stir until combined
Press into the tin, making sure it is even. Chill in the fridge to set whilst you make the caramel.