Lightly brush or spray a 9 x 13 inch baking dish with cooking spray.

Place butter in a large dutch oven or pot over medium low heat. Stir to melt then add 8 cups of mini marshmallows to pot. Reserve 3 cups mini marshmallows for later.

Stir marshmallows and butter together until melted and smooth. Stir in vanilla and add salt. Stir to combine. Remove from heat and swiftly stir in cereal. After a few stirs, add remaining 3 cups mini marshmallows to the warm mixture. Stir gently and not too much. The marshmallows will melt just slightly. Transfer mixture to buttered pan. Add a little softened butter to your hands and gently press treats into pan without pressing too flat. Use a plastic knife and gently cut into 9 rectangles while still warm. Let firm up in the refrigerator for 15 minutes.

Place individual rectangle cut Krispie Treats onto some parchment paper on a counter top. Get graham cracker sheets ready, I sized them to my Krispie Treats, trimming with a sharp knife if needed.

Melt chopped chocolate or chips in a heat proof bowl for 60 second intervals, stirring until melted and smooth. Working quickly, in batches of 3 treats at a time, spread an even layer of chocolate over the treats. Gently press graham cracker sheets over melted chocolate. I spooned some of the melted chocolate into the corner of a ziplock baggie, snipped the end and used as a “pen” to drizzle chocolate over the graham crackers. Once drizzled over graham crackers, place marshmallows on top along with some chocolate chunk pieces. Drizzle more melted chocolate over top of the marshmallows and chocolate chunks. Let chocolate set and serve!