Undated) -- Today is the Cookie Monster's favorite day of the year because it's national chocolate chip cookie day. The creation of the beloved cookie is credited to baker Ruth Graves Wakefield who accidentally made the cookies while working at the Toll House inn in 1938. She was planning on making chocolate cookies but the chocolate she used did not melt, but instead left chocolate chunks and created the chocolate chip cookie. Wakefield agreed to let Nestle use her recipe on the back of their chocolate chips in exchange for a lifetime supply of free cookies.