Put 7 cookies in a resealable plastic bag and crush into crumbs with heavy pan. Brush the bottoms and about 1 inch up the sides of 6 parfait glasses with butter. Add a spoonful of crumbs to each and roll them around the insides of the glasses; pour out the excess crumbs and reserve for topping. Refrigerate the prepared glasses.
Put 3/4 cup confectioners' sugar, the pumpkin, 1-1/2 teaspoons bourbon and the nutmeg in a food processor. Pulse until smooth, about 1 minute.
Put the white chocolate chips in a microwave-safe bowl and microwave at 50 % power until melted, about 1 minute, stirring halfway. Add to the pumpkin mixture and process until combined. Transfer to a large bowl.
Beat 1-1/2 cups cream in a bowl with a mixer until soft peaks form; fold into the pumpkin mixture until smooth. Divide among the prepared glasses and refrigerate until ready to serve.
Beat the remaining 1/2 cup cream with a mixer until foamy. Add the remaining 1 tablespoon confectioners' sugar and 1 teaspoon bourbon and beat until soft peaks form. Top the parfaits with the whipping cream, reserved cookie crumbs and the remaining 6 cookies.