Try to guess why is fluffy and airy vanilla custard cake "Kremsnita" (Cream Slices, Cremeschnitte) the most popular dessert in Croatia?
Mix cornstarch, flour, egg yolks, 12 Tbsp sugar, vanilla, rum and a few tablespoons cold milk.
Beat egg whites until stiff. Add 8 Tbsp sugar. Fold into the custard.
Place one layer of puff pastry on bottom of a 9x13 inch (23x33 cm) baking dish. Spread evenly with custard. (You can add a layer of whipped cream on top of custard, if you like.) Cut the second pastry sheet into 15 squares. Lay the squares over custard, pressing down slightly. Refrigerate. Sprinkle Kremsnite / Cremeschnitte with powdered sugar on top before serving.