Char marshmallows. To do this either stick them on a metal skewer or use a fork. Using a gas stove on medium/high or a blow-torch (if you are so lucky to have one) char the marshmallows so they are ooey gooey campfire style.
After all the pancakes are cooked, the Nutella syrup is melted and the marshmallows are charred, assemble the stacks. Place one pancake on a plate, spread Nutella on it and sprinkle mini chocolate chips over top, do this as many more times as you would like, depending on how high you want your stacks. For the final layer, drizzle the Nutella syrup over the top and down the sides of the stack. Top with chocolate chips and the charred marshmallows.