1-First, line a 9×13-inch pan with parchment paper or butter it to prevent sticking. In a large heavy-bottom saucepan over medium heat, stir the butter, sugar, and corn syrup until it boils, which takes about 5-10 minutes.

2-Once the mixture is boiling, slowly add the evaporated milk, one can at a time, over 12-15 minutes per can. Keep stirring constantly to maintain a steady boil and avoid curdling, as this step is crucial for the texture. Use medium heat to keep everything consistent and prevent any issues like separation.

3-Continue stirring and scraping the sides of the pan until the mixture hits the firm ball stage, around 240-245°F. You can also use the ice water test by dropping a bit into ice water; it should form a ball that’s firm yet pliable. This method works well regardless of your location’s altitude or humidity.

4-Remove the pan from the heat and stir in the vanilla to add that final flavor boost. Pour the mixture into your prepared pan and let it refrigerate until firm, ideally overnight for the best results. Once it’s set, cut it into pieces at room temperature and wrap them individually in wax paper if you like.