Line a baking sheet with parchment paper and lightly butter it. This prevents the candy from sticking when it cools later.

In a heavy saucepan, combine sugar, molasses, corn syrup, and water. Stir over medium heat until the sugar dissolves completely.

Attach a candy thermometer and cook the mixture until it reaches 250°F (hard-ball stage). This ensures the candy sets properly once cooled.

Remove from heat and quickly stir in peanut butter, butter, vanilla, and salt until smooth. Mix well to combine.

Transfer the heated mixture onto the baking sheet that has been prepared. Let it cool slightly, then cut into small squares while it’s still pliable.