Add butter cookies to a blender and blend well to crush the cookies. Once a coarse cookie mixture is formed, take out the cookie crumbs in a bowl.
Now add peanut butter, sugar and butter to a pan. Keep on medium flame, mix well and cook for a few minutes or until the sugar is combined well with the peanut butter and butter.
Now add cookie crumbs to the peanut butter mixture and mix well. Cook for 2-3 minutes to form a smooth mixture.
Pour the mixture into a greased tray and even it out. Slide the tray in the fridge and let it rest for a while. Check after 1 hour. The peanut butter mixture should have set by now.
Use a sharp knife and cut the peanut butter slab into small squares. Your Peanut Butter Toffees are now ready to be served.