Line a 9x9 inch baking pan with parchment paper, leaving some overhang for easy removal.

In a medium saucepan, mix 2 cups granulated sugar and 1/2 cup unsweetened cocoa powder over low heat until evenly combined.

Add 1/2 cup milk and 1/2 cup unsalted butter, stirring until the butter melts completely.

Bring the mixture to a boil over medium heat, stirring continuously.

Let it cook for about 5 minutes, stirring frequently, until it reaches the soft ball stage.

Remove from heat and stir in 1 teaspoon vanilla extract, 2 cups Jet Puffed marshmallows, and 1 cup chocolate chips until smooth.

Carefully pour the hot fudge mixture into the prepared pan.

Allow the fudge to cool at room temperature for about 2 hours, then cut into squares.