Preheat your oven to 350°F (175°C). Line two baking sheets 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. Stir in the vanilla extract.

In a separate 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 chocolate chips, mini marshmallows, and chopped nuts until evenly distributed.

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

Bake in the preheated oven for 10-12 minutes, or until the edges are golden brown. The centers may look slightly underbaked; they will firm up as they cool.

Allow the cookies to cool on the baking sheets for 5 minutes before transferring them to wire racks to cool completely.