French for "kneaded butter." It's similar to a roux in that its basic ingredients are just flour and butter but beurre manié isn't cooked. Instead, softened butter and flour are kneaded or mashed together until combined, then whisked into hot sauces or soups.

Spruce Eats https://www.thespruceeats.com/make-a-beurre-manie-1375421