Preheat oven to 375°F and line baking sheets with parchment paper or silicone baking mats.
In a small bowl combine all-purpose flour, baking soda and salt.
Use a stand mixer fitted with the paddle attachment to cream softened butter, granulated sugar and brown sugar until light and fluffy.
Add eggs one at a time and vanilla until just combined. Scrape the sides of the bowl.
Add the dry ingredients all at once and mix on low speed until almost combined (there should still be streaks of flour). Then add the chocolate chips and mini marshmallows and mix on low speed until just combined. Do not over mix the dough because it will make the cookies tough.
Using a 3 tablespoon cookie scoop, scoop dough onto lined baking sheets (be sure to adjust the baking time if your cookies are smaller/larger). If desired press extra chocolate chips and mini marshmallows onto the tops of each cookie dough ball.
Bake cookies for 11 minutes then cool on the baking sheet. The cookies will still look slightly raw when they come out but will continue to bake as they cool.
Notes
Weigh your ingredients using a kitchen scale! Measuring ingredients by volume is not accurate.
Butter: I recommend using unsalted butter. You can use salted butter, just be sure to omit the 1 tsp salt.
Store Marshmallow Chocolate Chip Cookies in an airtight container for up to 5 days at room temperature.
Nutrition: the provided nutritional information is an estimate per serving. Please read my Nutrition Disclaimer for more information.