Divide half of the sponge fingers amongst 4 glasses; breaking up the sponge fingers is essential. Then, drizzle with the cold coffee. Chop the hazelnuts with the bamix® processor and toast them in an ungreased pan. Set aside 1 tbsp of the nuts for the garnish. Finely chop half the tonka bean with the bamix® processor. Whip the cream with the bamix® beater until stiff and mix with the mascarpone, sugar, hazelnut liqueur, chopped tonka bean and toasted hazelnuts. Pour half of the mixture over the soaked sponge fingers. Now, arrange the second layer of sponge fingers in the glasses and pour the rest of the crème on top. Garnish with the hazelnuts and leave to set in the fridge for at least 2 hours.