Preheat oven to 375 degrees.
Spray cake pans with cooking spray and line the bottom of each with parchment paper.
Mix all ingredients together then fill each cake pan about a half inch full (if you are using 6 inch pans you will have extra and if you are using 8 inch pans divide the mixture evenly between all three pans). Press down firmly so the graham cracker mixture is packed down evenly.
Bake for 5 minutes then set aside to fully cool before you add the cake batter. We suggest making the cake batter while the crust cools.