Step 1

Butter an 8-inch non-stick baking dish (or line with buttered parchment paper) and set aside.

Step 2

In a medium saucepan over medium heat, heat the butter and peanut butter until the mixture comes to a boil. Remove from the heat.

Step 3

Add the salt and vanilla extract, then stir in the powdered sugar until smooth and no lumps remain.

Step 4

Pour the fudge mixture into the prepared pan and smooth the top. Press a piece of plastic wrap directly on the fudge and refrigerate until set, at least 1 hour. Cut into squares and serve. Fudge can be stored at cool room temperature in an airtight container for up to 1 week, or in the refrigerator for up to 1 month.