Melt butter in a medium sized sauce pan over medium flame.
Once melted, add can of evaporated milk and slowly pour in sugar, cup by cup. Stir to combine.
Continue stirring over medium flame, being careful to scrape the bottom, so the mixture doesn’t scorch.
Stir until the mixture starts to boil, then turn heat to low and set timer for 12 minutes.
Stir non-stop until 12 minutes is up, be sure to constantly scrape the bottom of pot to prevent scorching.
When time is up, remove from heat and add in vanilla. Be careful, vanilla will cause the mixture to bubble and pop.
Continue stirring and add in chocolate or peanut butter chips.
Beat mixture by hand until it starts to get tougher to stir, as the candy begins to set up. Once the consistency is right (hard to stir), pour into a greased pan and allow to cool.
Once fully cool, slice and enjoy!