Preheat the oven to 350°F (175°C).
In a bowl, mix graham cracker crumbs, sugar, and melted butter until well combined.
Press the mixture into the bottom of a muffin tin, filling 12 cups.
Bake the crust for 8-10 minutes until lightly golden.
Remove the crust from the oven and let it cool for 5 minutes.
Sprinkle 1 cup of chocolate chips over the crust, followed by the mini marshmallows.
Return the muffin tin to the oven and bake for an additional 5-7 minutes, or until the marshmallows are golden and puffed.
Cool completely before removing from the muffin tin.
Enjoy your s'mores cups as they are, or garnish with extra chocolate drizzle.