Preheat the oven to 350 degrees. Line a baking dish with parchment paper and then add cooking spray.
Combine the butter, brown sugar and flour in a bowl until a dough forms. Press it into the bottom of the baking dish and bake for 15 minutes.
As the crust cools, combine the eggs, brown sugar, cookie butter, vanilla, flour and salt. Pour into prepared crust and bake for 30-35 min or until it is set.
Let it cool completely and then remove with the parchment from the baking dish. Slice into bars (they will crinkle as you cut it) and enjoy!