In a medium bowl, whisk together flour, graham cracker crumbs, baking powder, baking soda, and kosher sea salt. Set aside.

Beat butter, brown sugar, and granulated sugar until light and fluffy. Add vanilla extract and egg, mixing until smooth.

Gradually mix in the dry ingredients until just combined, avoiding overmixing.

Fold in mini marshmallows, chocolate chips, half of the chopped chocolate, and coarse graham cracker chunks.

Transfer dough to an airtight container and refrigerate for at least 3 hours.

Preheat oven to 350°F. Scoop tablespoon-sized portions onto lined baking sheets, bake for 6 minutes, add toppings, then bake for an additional 5-7 minutes.

Let cookies rest for 5 minutes on baking sheets, then transfer to a wire rack to cool completely.