Custard Slices are a well-known Croatian dessert called Kremsnite. They're a delicious combination of custard, puff pastry, and whipped cream that's a wonderful, light dessert at the end of the day. This recipe serves twenty people, so you can easily make it for a party or a potluck. Make sure you save some for yourself though, because this treat will get eaten quickly! The vanilla custard is also lightly flavored by rum, which provides a richer taste without overwhelming the taste of the dish.