What began as a 5-cent snack sold during the Great Depression has grown into one of Little Debbie’s best-selling treats more than 90 years later. The Oatmeal Creme Pie was Little Debbie’s first snack cake, tracing its roots to 1935, when O.D. McKee developed the treat after selling baked goods from the back of his 1928 Whippet, according to Little Debbie’s website. In 1934, the McKees had purchased a bakery near Chattanooga, Tennessee, using the family car as collateral, according to the website. “Money was so tight, they had to put up a sheet near the back of the bakery for the…