Cookie recipe here.
Salted caramel frosting recipe here. (I upped the sugar and cream in the caramel to 1/3 c. and the salt to 1 1/2 tsp.)
White Chocolate-Hazelnut Mousse
2 whole eggs + 1 egg yolk
1/4 c. sugar
5 tbsp. Frangelico liqueur
7 oz. white chocolate
1 c. heavy cream
Finely chop the chocolate.
Whisk the eggs, sugar and 3 tablespoons of the Frangelico together in a heatproof bowl. Put the bowl over a pan of barely-simmering water and whisk continously until the eggs lighten in color, thicken and double in volume (you can also check the temp, it should be around 135).
Take the eggs off the heat. Mix in the chocolate and whisk until smooth. Let cool to room temp, whisking occasionally to help things along.
Beat the heavy cream and remaining Frangelico to medium-stiff peaks and fold the whipped cream into the cooled chocolate mixture in two batches, being careful to keep as much volume as possible.
Refrigerate the finished mousse for at least 6 hours, or until stiff enough to spread.