Combine cookie crumbs and butter; press onto bottom of 9x13 baking dish; set aside.
In medium saucepan, combine 1/2 the chocolate chips, condensed milk and vanilla over medium heat; stir while cooking, until chips are melted. Pour mixture evenly over cookie crust. Top with nuts and remaining chocolate chips.
Bake 20 minutes; or until set. Cool then cut into bars.