S'mores Pumpkin Cupcakes

Preheat oven to 350 degrees F. Line a 12-cup muffin tin with cupcake liners. Meanwhile, combine graham cracker crumbs, butter, sugar, and salt in small bowl. Press about 1 tablespoon of the mixture into each cupcake liner to make mini crusts. In a large mixing bowl, combine the yellow cake mix with canned pumpkin. Top graham cracker crusts with batter. Bake until a toothpick comes out clean, 22 minutes. Let cool slightly while you make ganache: Add chocolate chips to a heatproof bowl. In a small saucepan over low heat, heat heavy cream just until it bubbles. Pour over chocolate chips and let stand 2 minutes, then whisk until smooth. Top each cupcake with a spoonful of ganache, letting some drip down the sides, then add a marshmallow and return to oven. Bake until marshmallow is golden, about 5 minutes more. Garnish with graham cracker crumbs.