A dessert can most definitely be a snack. You could easily have fruit as a snack and fruit can be considered dessert. Also some packaged desserts like caramel corn or a snickers bar is often eaten as...
Pancakes and poffertjes (really small fluffy pancakes) are sweet snacks. Vla is a popular dessert (like a custard but eaten cold an not so thick) and comes in lots of flavours (vanilla, choclate...