Mix the Guma pâtisserie cream for about 3-4 minutes until creamy.
Place the mascarpone, powdered sugar and a dash of advocaat in a bowl and also mix briefly until creamy. Fold the whipped pâtisserie cream into the mascarpone cream by hand.
Now add the milk, espresso and the rest of the eggnog to a bowl and mix a little. Dip the biscuits one by one into the milk mixture and line a baking dish with them. Pour half of the cream on top and smooth it out. Use the remaining biscuits to make a second layer and spread the rest of the cream on top again.
Refrigerate the finished tiramisu to set (4 hours or overnight) and sprinkle with cocoa before serving.