Preheat oven to 350 degrees. Grease an 8x8 or 9x9 pan; set aside.

In a large bowl, combine graham crackers, brown sugar, and unsalted melted butter. Stir to combine, until the graham cracker crumbs are moistened. Press the graham cracker mixture into the baking pan firmly, creating an even layer. Bake for 8 to 10 minutes and cool completely.

In a small saucepan, heat heavy cream over low heat. When the cream is hot, pour over chocolate in a medium bowl. Let sit for 1 minute, then stir until smooth. Stir in the raspberry puree, then pour the raspberry ganache over the graham cracker crust.

Sprinkle the mini marshmallows on top of the ganache (or if you have time and patience, make pretty perfect rows of marshmallows). Broil on Low until the marshmallows are toasted (I don’t give a time here because every oven is different, just watch them until they are toasted!).

Refrigerate for at least 4 hours until the ganache is set. Cut and serve.