These proportions push the flour’s starch and the eggs’ proteins to their limit for holding the fat and sugar in a tender, light scaffolding; more butter or sugar collapses the scaffolding and makes dense, heavy cakes. And because cake batter must be filled with many small bubbles without the help of yeasts, which generate gas too slowly for the batter to hold them, traditional cake making was hard work. In 1857, Miss Leslie described a technique by which the cook could beat eggs “for an hour without fatigue” and then added: “But to stir butter and sugar is the hardest part of cake making. Have this done by a manservant.” Fannie Farmer warned in 1896 that “A cake can be made fine grained only with long beating