Demi-glace warm. At this point, the espagnole is prepared, and when it is finished, the brown stock is added in equal portions to the espagnole. Demi-glace keeps very well, about six months refrigerated or almost indefinitely frozen. Due to the considerable effort involved in making the traditional demi-glace, chefs commonly substitute a simple "jus lié" of veal stock or to create a simulated version, which the American cookbook author Julia Child referred to as a "semi-demi-glace"(i.e. sans espagnole sauce). However, even today, many chefs who prepare French "haute cuisine" use a demi-glace prepared in their own kitchen. Concentrates and mixes, mostly
French cuisine cooks' guild regulations allowed for this movement. During the 16th and 17th centuries, French cuisine assimilated many new food items from the New World. Although they were slow to be adopted, records of banquets show Catherine de' Medici (1519–1589?) serving sixty-six turkeys at one dinner. The dish called cassoulet has its roots in the New World discovery of haricot beans, which are central to the dish's creation, but had not existed outside of the New World until its exploration by Christopher Columbus. Haute cuisine (, "high cuisine") has foundations during the 17th century with a chef named La Varenne. As