Wafers round or square (I typically buy mine at the polish store)
1 can of sweetened condensed milk
In a medium sauce pan with high sides pour in cold water only leaving about an inch of room at the top.
Take your can of condensed milk and remove the label. Submerge the can under the water so that it stands up straight.
Turn your stove down so that the water is at a simmer and let it simmer for 3 hours (keep on eye on the water because it will evaporate so if it seems like the water is getting too low make sure to add some hot water to the sauce pan).
After 3 hours remove the can from the water and let cool for several hours.
After the can has cooled completely open the can and cover a piece of wafer with your toffee topping. Place another wafer over toffee and repeat the process until you are completely done layering the wafer and toffee.
Cover in aluminum foil and place something heavy over the top to help the mixture set for an hour or so.