In a medium saucepan, melt the butter over low heat. Once melted, add the peanut butter and stir until smooth and creamy. Keep the heat gentle — you don’t want it to boil.
When the mixture looks silky and well-blended, remove it from the heat. Stir in the vanilla extract and a pinch of salt.
Using a spatula or wooden spoon, gradually add the powdered sugar to the warm peanut butter mixture
At first, it’ll look like it’s separating, but keep mixing — the fudge will come together and become smooth and spreadable.
Pour the mixture into the prepared pan and spread it evenly with a spatula.
If you’re adding toppings, now’s the time. Sprinkle chopped peanuts for crunch or sea salt flakes for that sweet-and-salty contrast.
Refrigerate the fudge for 1–2 hours, or until firm enough to slice.
