01 -
Roughly chop the Graham crackers and Hershey's bar. Tear the mini marshmallows in half to prevent them from puffing excessively during baking.
02 -
In a bowl, combine the flour, salt, baking powder, baking soda, and cornstarch. Whisk together and set aside.
03 -
Using a stand or hand mixer, beat the butter and sugars until creamy, approximately 2 minutes. Add the egg and vanilla extract, mixing until combined. Scrape the sides of the bowl and mix again.
04 -
Gradually add the dry ingredient mixture to the butter mixture. Beat on low speed until just combined.
05 -
Reserve a handful of the torn marshmallows and set aside. Add the remaining marshmallows, chocolate chips, and chopped Graham crackers to the dough. Mix on low speed until just combined, being careful not to overmix.
06 -
Refrigerate the dough for at least 1 hour.
07 -
Preheat the oven to 350°F (175°C). Portion out approximately two-tablespoon-sized pieces of dough, roll into balls, and place on a parchment-lined baking sheet approximately 2 inches apart. Bake for 8 minutes.
08 -
Top the partially baked cookies with the reserved marshmallows and pieces of Hershey's bar. Return to the oven and bake for an additional 2-3 minutes. If any cookies spread unevenly due to excess marshmallows, use a round cookie cutter or knife to reshape them.
09 -
Allow the cookies to cool completely on the pan before serving.