Brownies are categorized as bar cookies because they are eaten by hand rather with a fork and are thicker and more cake-like than cookies. The first brownies were sold at the Columbian Exposition of 1893, made by the Palmer House, a Chicago hotel.
A recipe for the precursor to brownies, flavored with molasses, appeared in the Fannie Farmer "Boston Cooking-School Cook Book" published in 1896. When the book was reprinted in 1905, the recipe was modified into chocolate brownies. However, the first printed brownie recipes appeared in cookbooks in 1904.
Early recipes indicate the brownie may have originated in Bangor, Maine. Brownies grew in popularity during the 1920s. As of 2014, some modern brownie recipes include beets, beans, carrots, spinach or melatonin.
There are several days of the year named in honor of the brownie: January 22 is National Blonde Brownie Day, February 10 is National Cream Cheese Brownie Day, May 9 is National Butterscotch Brownie Day and December 8 is National Brownie Day.
In 2011, chefs in New York created the world's largest chocolate brownie, weighing 3,000 pounds, using 750 pounds of chocolate chips, 500 pounds of butter and 500 pounds of flour, to raise funds for the families of victims of the World Trade Center attacks.