Preheat oven to 350 degrees.

Pulse graham crackers in the food processor until the turn into crumbs. Add the powdered sugar and pulse to combine. Turn the food processor on and pour in the melted butter. It will start to combine into coarse crumbs.

Divide the crumb mixture evenly among 24 mini muffin cups. Press down to form shallow cups.

Bake for 3-4 minutes until they bubble around the edges.

Remove from the oven and place on chocolate rectangle into each cup. Place one marshmallow half, cut side down into each cup.

Turn the oven to broil. Return the pans to the oven and broil until the marshmallows are golden brown.

Cool for about 15 minutes and then carefully remove from the pan.