Although the name may be derived from avocado:
According to several makers, such as Verpoorten and Bols, and the Oxford companion to Sugar and Sweets, its origins can be traced back to “abacate”, an alcoholic beverage of the indigenous people in Brazil, which was made with. Dutch colonials of northern Brazil introduced this beverage to Europe as “advocat/advocaat”. As avocados could not grow in northern Europe, they were replaced with egg yolk, thought to have a similar taste and consistency, and the name derived from the avocado stuck, although the drink no longer contains any.