1Preheat oven to 425F (220°C). Line or grease a 1.5 pound loaf pan.
2Brown the butter over medium heat until golden and nutty. Remove from the heat, stir in the heavy cream, and let cool.
3In a large bowl whisk together the browned butter, mashed bananas, granulated sugar, brown sugar, and eggs until smooth. Add vanilla, sour cream and mix until combined.
4In a separate bowl, whisk together the flour, baking soda, and salt.
5Fold the flour and crushed graham crackers into the wet ingredients until just combined. Gently fold in the chocolate chips and mini marshmallows.
6Bake at 425°F (220°C).
7Without opening the oven, reduce temperature to 350°F (175°C). Continue baking until a toothpick comes out with moist crumbs, tenting with foil if needed.
8Remove the loaf from the oven and immediately top with mini marshmallows and crushed graham crackers. Return to the oven until the marshmallows are lightly toasted.
9While the loaf is still hot, top with pieces of Hershey’s chocolate and let them soften from the residual heat.
10Cool in the pan before transferring to a wire rack.