Preheat the oven to 375°F (190°C). Line two baking sheets with parchment paper.
In a large bowl, cream together the softened butter, granulated sugar, and light brown sugar until light and fluffy, about 3 minutes.
Beat in the eggs one at a time, ensuring each is fully incorporated before adding the next.
Stir in the vanilla extract.
In a separate bowl, whisk together the all-purpose flour, baking soda, and salt.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined.
Fold in the semisweet chocolate chips gently.
Using a tablespoon, scoop cookie dough onto the prepared baking sheets, spacing them about 2 inches apart.
Press 3-4 mini marshmallows onto the top of each cookie dough ball, gently pressing them in so they stick.
Bake in the preheated oven for 10-12 minutes, or until the edges are golden but the centers remain soft.
Remove from the oven and allow cookies to cool on the baking sheets for 5 minutes before transferring to a wire rack to cool completely.