Mix the MyDay sour cream and Cremio whipping cream separately, then combine them gently until you have a fluffy mixture. Beat the mascarpone with powdered sugar to taste, and fold this mixture into the cream mixture until well combined. Mix the coffee with the rum and let it cool.
Choose a suitable dish so that the ladyfingers will form 3 layers and the cream can be used to spread between and on top of the ladyfingers. Alternate layers of soaked ladyfingers with the cream. Finish with a layer of cream and a dusting of cocoa to create a festive touch. Serve the delicious Christmas tiramisu with a cup of flavorful coffee.