Butter a 20 cm cake pan and put parchment paper on the bottom to make sure nothing sticks.
Then, mix the cookies, the hazelnuts and the melted butter in a mixer.
Pour half into the bottom of the pan, then pour the rest to make the sides of the cake.
Let rest in the refrigerator for 10 to 15 minutes.
Preheat the oven to 355°F.
Mix the Philadelphia cheese and the sugar with an electric mixer. Then add the eggs one by one without stopping mixing.
Mix separately the flour and the cream and add it to the Philadelphia cheese and sugar mixture. Then add the Irish cream liqueur or syrup.
Pour the mixture into the pan.
Place the cake on a baking sheet and bake 40 to 50 minutes.
Put in the refrigerator for several hours afterwards.
For the topping, put the sugar and 185 ml of water in a saucepan and melt the sugar.
Let the syrup simmer for 10 to 12 minutes or until a golden color is obtained.
Off the heat, add the coffee to the caramel.
Dip the hazelnuts one by one in the caramel with two spoons and place them on parchment paper to harden.
Then, whip the cream until you get whipped cream.
Unmold the cake and decorate with whipped cream and caramel hazelnuts.