Start by lining a 9x9-inch baking dish with parchment paper.
In a large pan, melt your butter over medium heat. Once melted, add in the 4 cups of mini marshmallows and stir constantly until they're completely melted and smooth. The smell alone will have you hooked!
Remove the pan from heat and stir in the vanilla for that extra touch of flavor. Then, fold in the Rice Krispies, Golden Grahams, and half of your remaining mini marshmallows (½ cup). Mix until everything is well combined.
Pour the mixture into your prepared baking dish and press it down evenly. Don’t press too hard—you want these to stay nice and chewy, not rock solid.
While the mixture is still warm, sprinkle the chocolate chips and the remaining mini marshmallows (½ cup) over the top. Gently press them down so they stick, and voilà! You’ve got that s’mores vibe going on.
Let the treats cool for about 15 minutes, then cut into squares and dig in! If you manage to have any left over, you can store them in an airtight container for up to five days.