Slice the butter into tablespoon-sized pieces. Place the pieces of butter in a pan over medium heat. Stir the butter consistently to keep it moving the entire time. Once melted, keep stirring until it begins to foam and sizzle on the edges, about 5-8 minutes from when you first started. The butter should turn a golden-brown color. Immediately remove the butter from the heat and pour into the prepared bowl to cool.
For the Cookies:
Add the brown butter, brown sugar, granulated cane sugar, and egg into the bowl of a stand mixer. Whisk on medium speed for 2 minutes.
In a separate bowl, mix the flour, baking soda, baking powder, and salt until evenly combined. Add the flour mixture and vanilla extract into the mixing bowl. Mix until just combined.
Add the chopped chocolate, marshmallows, and crushed graham crackers. Mix until just combined once more.
Roll out the dough into a 3" log, then cover with plastic wrap and chill in the fridge for 30 minutes.
Preheat oven to 350F. Line a large baking sheet with parchment paper.
Slice the cookie dough into 1" circles (about 2 tablespoons cookie dough per cookie). Place on the prepared pan.
Bake for 8-10 minutes, or until edges are turning golden brown and centers are set. Allow to cool on the pan for at least 5 minutes. Enjoy!