In a food processor, add wafer cookies and process until ground. Add powdered sugar, peanut butter, and melted butter and process until smooth.
Spread into a 9x13" pan lined with tin foil. Set in the freezer to firm up while you melt the chocolate.
Combine chocolate chips and milk and microwave on high in 30-45 second intervals, stirring each time, just until the chocolate is melted (don't overdue it!). I did 45 seconds, 30 seconds, 20 seconds and it was perfect.
Spread evenly over bars and refrigerate until firm (you can put them in the freezer if you're in a hurry!). Slice into bars and serve. I recommend storing in the fridge or freezer.
Notes
*If you can't find the vanilla wafer cookies (too bad!), you can substitute the same weight of say a Nilla wafer cookie or graham cracker crumbs if necessary. *This is an easy recipe to halve if a 9x13" pan is too large or too much temptation!