Preheat an oven to 190 degrees C. Line baking trays with baking paper. In a bowl, mix the flour, cocoa, bicarb soda and salt.
Beat the butter, white sugar and brown sugar together in a bowl with an electric mixer until soft and creamy, then beat in the eggs, vanilla essence and coffee liqueur. Gradually beat the flour mixture into the butter-sugar mixture until well combined.
Stir in the hazelnuts, dark chocolate chips, milk chocolate chips, and white chocolate chips until evenly distributed through the dough. Drop by rounded teaspoons, about 5cm apart, onto the prepared baking trays.
Bake in the preheated oven until the edges are slightly browned, 8 to 10 minutes. Allow the biscuits to cool on the baking tray for 1 minute before removing to a wire rack to cool completely.