01 -
Preheat oven to 350°F. Spray a 9x13 inch baking dish with non-stick cooking spray or line with parchment paper for easier removal of bars.
02 -
In a medium bowl, mix together graham cracker crumbs and melted butter until well combined. Press this mixture firmly and evenly into the bottom of your prepared baking dish to form the crust.
03 -
Pour the sweetened condensed milk evenly over the graham cracker crust, making sure to cover the entire surface.
04 -
Sprinkle half of the mini marshmallows (1 cup), all of the chocolate chips, and all of the graham cracker pieces evenly over the condensed milk layer.
05 -
Bake for 15 minutes until the edges start to bubble and the marshmallows begin to puff up and turn golden.
06 -
Remove from oven and sprinkle the remaining cup of mini marshmallows over the top, covering any exposed areas.
07 -
Return to the oven and bake for an additional 10-15 minutes until the top marshmallows are toasted golden brown and the edges of the bars are set.
08 -
Remove from oven and immediately place the broken chocolate bar pieces on top of the hot marshmallows so they begin to melt slightly.
09 -
Allow the bars to cool on a wire rack for at least 15 minutes before cutting. For cleaner cuts, let them cool completely, though they will still be deliciously gooey.