This food holiday celebrates a pie made with a custard filling lightened up with whipped cream and thickened with gelatin. Bavarian cream was probably concocted by French chefs working for Bavarian royalty in the 17th century. Adding Bavarian cream to a pie began at least in the 19th century but grew more popular in the 1900s when instant pudding and custard mixes made them easier to prepare. Coconut cream pie and Boston cream pie are both variations of the Bavarian cream pie.