Step 1: Prepare a 9x9 inch baking pan by lining it with parchment paper. This will make it easier to remove the fudge once it's set.

Step 2: In a medium saucepan, combine the sweetened condensed milk, chocolate chips, and butter. Heat the mixture over medium-low heat, stirring constantly, until the chocolate chips and butter have melted and the mixture is smooth.

Step 3: Remove the saucepan from the heat and stir in the Jet-Puffed Marshmallow Creme, vanilla extract, and salt. Keep stirring until everything is well combined and the marshmallow creme has melted.

Step 4: Pour the fudge mixture into the prepared baking pan and spread it evenly with a spatula.

Step 5: Chill the fudge in the refrigerator for at least 2 hours, or until it's firm to the touch.

Step 6: Once the fudge is set, use the parchment paper to lift it out of the pan and onto a cutting board. Cut the fudge into small squares and serve.