In 1930, Ruth Wakefield was mixing a batch of cookies for her roadside inn guests when she discovered she was out of baker's chocolate. She substituted broken pieces of semi-sweet chocolate, expecting it to melt and absorb into the dough to create chocolate cookies. But the chocolate didn't absorb into the dough. When she removed the pan from the oven, Wakefield realized she had accidentally invented chocolate chip cookies. They were named "Tollhouse" after Wakefield's inn, and they remain the most popular variety of cookie in America.