Brown butter is a traditional French sauce made simply of heated, unsalted butter. Calledbeurre noisettein French, which translates to hazelnut butter, it is thusly named for its rich, nutty flavour. It’s often used in pastry making, and is classically paired with pasta in northern Italy. It can be used as a sauce for gnocchi, and tortellini—you really don't need to add anything else to it, but you can dress it up further with Italian sausage, shaved parmesan, or breadcrumbs, if you prefer.