Preheat your oven to 350 degrees F. Liberally grease a 13x9 rectangular baking pan with cooking spray; set aside.

In a large bowl, combine the pound cake mix, melted butter, beaten egg, and pumpkin pie spice with a spoon until moistened and mixture resembles coarse crumbs. Mixture will look shaggy but should hold together when pressed with your fingers. Press the mixture evenly into the bottom of the cake pan. Set aside.

In another large bowl, beat the cream cheese with a handheld electric mixer for 1 minute or until creamy and soft. Add in the condensed milk, pumpkin puree, eggs, and spice and beat until smooth and combined. Stir in the chopped Oreo cookie pieces. Pour the mixture into the prepared pan and smooth out the top.

Bake for 30-35 minutes or until the center is set and no longer jiggly. Cool the bars in the pan until room temperature, then refrigerate for at least 2 hours to firm up before cutting into bars. Garnish with whipped cream and more crushed Oreo cookie pieces.