Lancelot de Casteau or de Chasteau or de Chestea, also known as Anseau de Chestea (died 1613) was the master chef for three prince-bishops of Liège in the 16th century: Robert de Berghes, Gérard de Groesbeek, and Ernest of Bavaria and the author of a cookbook, the Ouverture de cuisine, often considered the first cookbook to go beyond medieval recipes and to codify haute cuisine.
de Casteau was born in Mons. As an adult, he lived in Liège. In 1557, he organized a banquet for the Joyous Entry of Robert of Berghes. He was admitted to the bakers' guild in 1562, to the mercers' (merchants') guild in 1567, and to the burghers in 1571. He married Marie Josselet alias de Herck in c. 1572, and they had a daughter, Jeanne.
A rich burgher, he owned much real estate, but starting in 1601, the prince-bishop no longer paid for his services, and his financial situation deteriorated, forcing him to live with his daughter and his son-in-law, a goldsmith named Georges Libert, who supported him.
He died in 1613.
de Casteau's book Ouverture de cuisine was published in 1604 and dedicated to Jean Curtius. The book is mentioned by multiple writers starting in the 18th century, but the last copy was thought to have been destroyed during the Napoleanic wars. In 1958, a private party offered a copy to the Royal Library of Belgium, which bought it. This is the only known copy.