Comment by lbreakjai

The nomenclature is quite loose. Speculaas and speculoos will be used interchangeably in parts of Belgium. "Spéculoos" will refer to both in the french-speaking part, while I anecdotally noticed Flemish people will use "speculaas" even for biscoffs.

That's why I only eat kruidnoten, less of a linguistic quagmire.