A vanilla slice, also known as a custard square, is a type of pastry. It consists of a thick custard, which is traditionally flavoured with vanilla or chocolate, and which is sandwiched between flaky puff pastry or filo pastry and iced with either vanilla, chocolate, strawberry, raspberry or passion fruit icing.and contains apricot jam It is one of a category of slices, both sweet and savory, common in the region.
The Australian vanilla slice has been described as a uniquely Australian food, but comparisons have been drawn to the mille-feuille, which may have originated in France.
An annual competition for the best vanilla slice baker is the Great Australian Vanilla Slice Triumph. Judging criteria include "when tasted, should reveal a custard with a creamy smooth texture and a balance of vanilla taste with a crisp, crunchy pastry topped with a smooth and shiny glaze/fondant".