Line a 9 x 9 pan with parchment paper on all sides. Set aside.
In a large microwave safe bowl, combine the Karo® Light Corn Syrup and evaporated milk. Mix will to combine. Microwave on high for 2 minutes and 30 seconds.
Remove the bowl from the microwave and stir in the chocolate chips until completely melted. If the chocolate does not fully melt, microwave the mixture for another 30 seconds to warm it up.
Add the vanilla, salt, and powdered sugar mixing until completely combined. The fudge will be shiny, but this will go away once it has set!
Fold in the mini marshmallows and graham cracker pieces. Do not over mix. Transfer the fudge to your prepared pan and spread into an even layer. Top with more marshmallows and graham cracker pieces if desired!
Place in the fridge for at least 2 hours to set! When ready to serve, use a clean sharp knife to slice the fudge. Enjoy!