Add gelatin packet into 1 cup milk, stir and set aside. Grind Oreos into fine crumbs by using a zippered bag and rolling pin, mini prep or food processor. Divide crumbs into two bowls with equal amounts in each bowl. Add melted butter to one bowl and mix until fully combined. Press firmly into an 8 x 8 cake pan, deep dish tart pan or individual pans. In a double boiler, add the milk and gelatin mixture, sugar, egg yolks, salt and vanilla. Whisk to combine and cook for 8 minutes, whisking often, until slightly thickened. Set aside to cool. Meanwhile, beat the whipping cream until stiff. When the filling has cooled, mix together the whipped cream and filling, gently whisking to combine. Pour filling into prepared cake pan with cookie crumb crust. Sprinkle second bowl of cookie crumbs over top of filling. Refrigerate 8 hours or overnight. Slice into squares and enjoy!