Heat the cream in a saucepan. Remove from heat and add the Kinder chocolates. Let them melt, then stir until smooth. Let cool until ready to assemble.
Tiramisu
Whisk the egg yolks with the powdered sugar until the mixture turns white.
Add the mascarpone and beat everything together until you get a smooth consistency.
Separately, whip the very cold liquid cream into whipped cream.
Gently fold the whipped cream into the mascarpone mixture using a spatula to maintain its airy texture. Transfer to a piping bag for easier decorating (optional).
Operating manual
Quickly dip a ladyfinger biscuit in the milk before placing it at the bottom of the glass. You will probably need to break it to adjust the amount.
Spread a layer of Kinder ganache. Note: the thicker the layer, the stronger the Kinder flavor (and therefore the sweeter the result) will be.
Using a piping bag or a spoon, fill with the mascarpone mixture.
Repeat a second time: ladyfinger biscuit soaked in milk, Kinder ganache then mascarpone mixture.
Sprinkle with unsweetened cocoa powder, and place a Kinder chocolate on top for decoration.
Refrigerate for at least 3 hours to allow the flavors to fully develop.
Notes
These Kinder tiramisu can be kept in the refrigerator for up to 2 days (no longer because they contain egg yolks).