Preheat oven to 350 degrees F. In a microwave-safe bowl, combine the butter and the milk. Heat on HIGH for one minute, then remove and stir. Continue microwaving in 20 second intervals, stirring after each, until butter has melted and milk is warm to the touch but not hot. Meanwhile, in a separate bowl, whisk together 3 cups of the flour, the sugar and the salt until combined.
In the bowl of a stand mixer, combine the yeast and the milk mixture and whisk together by hand. Add the flour mixture and egg all at once, and using the paddle attachment, beat on medium-low speed until combined. The dough will likely stick to the sides of the bowl, so sprinkle in the remaining ½ cup of flour to help the dough come together in a ball. Once the dough has pulled away from the sides and forms a ball, continue to beat the dough for 5 minutes on medium-low speed. Remove the dough hook and cover the dough with a damp cloth for 10 minutes to rest.
While the dough rests, prepare your filling: in a medium bowl, combine the brown sugar, graham cracker crumbs and cinnamon and set aside.
Turn the dough out onto the floured work surface. Using a floured rolling pin, roll the dough out into a large rectangle, about 14x9 inches in size. I did NOT measure my dough out; I only rolled it out and it turned out fine. Honestly, just roll into a decently-sized rectangular shape to your desired thickness. Spread the Hershey's Spread over the surface of the dough and evenly spread on the filling mixture.
Beginning at the longest edge furthest from you, begin rolling up the dough as tightly as possible. Pinch the final seam gently to help seal it up. Using a sharp knife, cut both ends of the dough (the doughiest parts you'll likely discard), and then begin evenly cutting the dough into about 12 equal pieces. You can also use unflavored dental floss to cut the dough, but I used a knife.
Place the rolls into two greased 9" cake pans. Cover the pans with damp towels and place the pans on top of your oven range for 25 minutes (or another warm place for them to rise). After the rolls have risen, uncover the dish and bake for approx. 15-20 minutes or until the rolls are golden, cooked through and bubbling.
In a small bowl, scoop out the marshmallow creme and microwave for approx. 30-45 seconds or until soft and smooth but not super liquidy. Pour/spread over the tops of the rolls evenly and sprinkle with marshmallow bits and chocolate chips. Serve!