Preheat your oven to 375°F. Prepare two baking sheets with parchment paper.

In a large bowl, beat together the butter, brown sugar, and white sugar for 2-3 minutes until it’s creamy.

Add the eggs and vanilla extract, mixing until well combined.

Mix in the flour, corn starch, baking soda, and salt just until the ingredients are blended.

Gently stir in 1 1/2 cups of the graham cracker pieces, 1 1/2 cups of the mini marshmallows, milk chocolate chips, and semi-sweet chocolate chips until evenly distributed.

Form dough into balls about 2-3 tablespoons in size and place them on the parchment-lined sheets, leaving enough space for the cookies to expand. Bake for 10 minutes.

Remove the cookies from the oven and quickly press 4-5 additional marshmallows, a few extra pieces of graham crackers, and pieces of Hershey bar onto each cookie.

Return to the oven for an additional 1-2 minutes. If you prefer, switch the oven to broil to lightly toast the marshmallows, watching carefully to prevent burning.

Let the cookies cool on the baking sheets for 2-3 minutes before transferring to a wire rack to cool completely. Store in an airtight container at room temperature for up to 4-5 days.