Speculoos or speculaas are sweet, spiced, caramelized biscuits or cookies, popular in the Netherlands, Belgium and beyond. They are commonly served with coffee. Biscoff – from 'biscuit' and 'coffee' – is an international brand name for these biscuits and a spread with the same flavours. Speculoos spreads are an early 21st century invention and can also be found under the generic name cookie butter. You can therefore use your favourite spread to make these brownies. Biscoff is the version that is popular and most widely available here in the UK.