Preheat your oven to 350 degrees F. Prepare a Bundt pan by greasing the inside with butter and then coating the butter with flour (be sure to tap out any excess flour).
In a medium bowl, whisk together the flour, baking powder, and baking soda. Set aside.
In a large bowl, beat together the sugar and butter until smooth and creamy, about 1 minute. Then whisk in the eggs, milk, and marshmallow fluff until they're fully incorporated into the cake batter.
Whisk in the flour mixture and graham cracker pieces making sure there are no dry clumps of flour in the batter.
Fold in the chocolate chips until they are evenly distributed throughout the batter. Pour the cake batter into the prepared Bundt pan.
Bake for 55 minutes, or until a toothpick inserted halfway between the wall and tube of the pan comes out clean.
Remove the cake from the oven and turn the pan over on a wire rack. Let the cake rest for about 10 minutes. Giving it that time to cool will help the cake release from the pan, but don't wait too long or the condensation in the pan can cause your cake to get soggy. Turn the pan right side up and run a knife around the inner and outer edges to release the cake before flipping the pan back over onto the wire rack to cool completely. Transfer to a serving platter once cooled.
Once cooled, this cake is great topped with chocolate ganache or chocolate frosting. My kids like to add on s'mores toppings like mini marshmallows, Hershey bars pieces, and more crumbled graham crackers, but this s'mores cake is delicious as is too.
Notes
If you don’t have salted butter on hand, add 1/4 teaspoon salt to the dry ingredients and use the same amount of unsalted butter.
You can store this cake in the fridge or on the counter for 4-5 days, as long as it is sealed in an airtight container.
Nutritional information does not include toppings.