Beat the egg yolks and sugar in a bowl with an electric mixer for 5 minutes then fold in the mascarpone.
In a separate bowl, whip egg whites until stiff peaks.
Fold the yolk-sugar-mascarpone mixture in with whites and set aside.
In a bowl, dilute the coffee with 2 tbsp of boiling water then add the cold water. Mix in the Frangelico and set aside.
In a large dish place a few spoonfuls of the mascarpone mixture to the bottom of the dish so the base is lightly covered.
Next, quickly dip the savoiardi two at a time into the coffee, allowing to sit for only 2-3 seconds) and lay them in the dish atop the mascarpone. Repeat until the base of the dish is completely covered with the biscuits.
Scoop a generous amount of the mascarpone mixture on top of the soaked biscuits until they are all covered. Sprinkle with a handful of the roasted hazelnuts.
Repeat steps 6 and 7 until you’ve used all your ingredients (or you’ve reached the top of your dish) finding with the mascarpone layer without the hazelnuts.
Dust generously with Organic Mountain cocoa powder on top and set in the fridge for at least 4 hours before serving.