Hazelnut liqueur is a rich, nutty liqueur made from hazelnuts. It has a distinct, toasty flavor with a hint of sweetness. Hazelnut liqueur is often used to add depth and complexity to cocktails, particularly in dessert-style drinks. It is a key ingredient in classic cocktails like the Nutty Irishman and can be paired with chocolate, coffee, or cream-based drinks. Frangelico is a well-known brand of hazelnut liqueur.