For the crust: Place a rack in the center of the oven and preheat to 350 degrees F. Grease the bottom and sides of an 8-by-8-inch baking pan with the cooking spray.
Place the cookies in a food processor and grind into fine crumbs. Reserve 1/2 cup of the crumbs for a later use.
Place the remaining crumbs in a bowl and stir in the melted butter and salt. Press the mixture into the bottom of the prepared pan evenly and transfer to the refrigerator to chill while you prepare the brownies.
For the filling: Place the chocolate and butter in a heatproof bowl set over a saucepan filled with 1 inch of water to make a double boiler. Set the double boiler over medium heat and stir to melt. Set aside to cool slightly.
In a medium bowl, mix together the melted chocolate mixture, the flour, granulated sugar, brown sugar, cocoa powder, salt, vanilla and eggs. Fold in the white chocolate chips, and then pour the batter into the chilled crust. Bake until set, 28 to 30 minutes.
Transfer to a wire rack to cool completely.
Sprinkle the reserved cookie crumbs over the finished brownie dish. Tuck the gummy worms on and into the cookie crumb "dirt." Cut the brownies into squares to serve.