Measure your flour correctly! Adding too much flour to the recipe is the most common mistake. The best, and easiest way to measure flour is by using a scale. If you don't have one then fluff your flour with a spoon, sprinkle it into your measuring cup, and use a knife to level it off.
If your cookies have a marshmallow blowout use a circle-shaped cookie cutter to corral them together as soon as they come out of the oven. You could also use a spatula or knife to push the edges back in.
These cookies are going to have that CLASSIC s'mores taste if you use the Hershey's chocolate bar so it's worth it to add to your shopping list.
Let the cookies cool on the baking sheet they'll be soft after coming out of the oven and need time to firm up.