Preheat oven to 350 degrees and spray a 12x9 jelly roll pan with non-stick cooking spray and line with parchment paper. Set aside.
In a large bowl, combine organic cookie mix and cold butter. Break apart the butter with a pastry cutter or your hands, until only small pieces remain. Add cold water and mix until a dough forms. Form dough into a flat disc and wrap in plastic. Chill 15 minutes or until firm enough to roll out.
In a large bowl, whisk eggs, then add pumpkin puree and remaining ingredients. Stir until smooth and well blended. Set aside.
Remove dough from freezer and flour a flat surface. Roll out dough to a rectangle shape, ¼” thick. Transfer dough to prepared pan and gently press and trim dough to fit pan.
Pour pumpkin mixture into crust, leaving about 1/8” of exposed crust. There may be some mixture leftover. Bake 40-45 minutes or until center is set and the crust is golden brown. Remove from oven and cool completely, about an hour.
Once cooled, lift parchment paper and remove bars from pan. Cut into squares and top with whipped cream, if desired. Enjoy immediately or refrigerate until ready to serve.