S'mores Banana Bread

Preheat oven to 350 degrees F. Butter a 9-x-5" loaf pan then line with parchment paper to create a lengthwise overhang on each long side of the pan. Butter and flour the parchment paper. In a large bowl, whisk together flour, graham cracker crumbs, baking soda, and salt. In another large bowl, combine sugar, butter, sour cream, vanilla, eggs until smooth. Pour wet ingredients over dry and stir until combined, then add mashed bananas. Fold in chocolate chips, just enough to incorporate. Transfer batter to prepared baking dish and bake until deeply golden and a toothpick comes out clean, about 60 minutes. Let cool at least 10 minutes, then transfer the loaf to a baking sheet. Preheat oven to broil. Drizzle the top of the loaf with melted chocolate and cover with marshmallows. Top with chocolate bar pieces and graham crackers. Broil for 1-2 minutes.