Line a 9x13 pan with parchment paper and set aside.
Melt the sugar, butter, corn syrup, and salt together in a large, heavy-bottomed pot over medium heat.
Once the mixture comes to a boil, add the evaporated milk a little at a time, taking 10-15 minutes per can and stirring constantly.
Once all the milk is added use a candy thermometer and bring the mixture to 238F-240F and not any hotter.
Immediately pour into the prepared pan and cool completely.
Cut and serve.
