Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.

In a large mixing bowl, cream together the softened butter, granulated sugar, and brown sugar until light and fluffy.

Add the eggs one at a time, mixing well after each addition, then stir in the vanilla extract.

In another bowl, whisk together the flour, baking soda, and salt.

Gradually add the dry ingredients to the wet mixture, mixing until just combined.

Fold in the mini chocolate chips, mini marshmallows, and crushed graham crackers.

Using a cookie scoop or tablespoon, drop rounded balls of dough onto the prepared baking sheet, spacing them about 2 inches apart.

Bake for 10-12 minutes or until the edges are lightly golden.

Remove from the oven and let cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.

While the cookies are cooling, prepare the frosting by beating together the softened butter and powdered sugar until smooth.

Add the heavy cream and vanilla extract, mixing until creamy and spreadable.

Once the cookies are completely cool, frost each cookie generously with the buttercream frosting.

Top with additional mini marshmallows and a sprinkle of crushed graham crackers.