Preheat oven to 350°F. Coat a rimmed baking sheet generously with cooking spray.
In a medium bowl, combine pancake mix and sugar, whisk until ingredients are incorporated with only a few small lumps.
In another bowl, combine eggs, oil, vanilla extract, milk and buttermilk; whisk until combined. Pour wet ingredients into dry ingredients, and mix until just combined but do not over mix.
Pour batter into prepared sheet pan, and spread out into an even layer.
Bake 14-16 minutes or until pancake is golden brown and a toothpick inserted in center comes out clean.
Cut pancakes into squares, and serve with butter and syrup, if desired.