A Boston bun, also known as a Sally Lunn, is a large spiced bun with a thick layer of coconut icing, prevalent in Australia and New Zealand.

Traditionally the bun contains sieved mashed potato,[1] and modern versions sometimes contain raisins or sultanas, the inclusion of which dates from the 1930s.

[2] Records for the sale of a product named "Boston Bun" can be found dating from the early 20th century.

[3] It is often served sliced and buttered, to accompany a cup of tea.

The origin of the name is unknown.