01 - Preheat oven to 350°F. Line baking sheets with parchment paper.
02 - In a medium bowl, whisk together flour, baking soda, and salt until well blended.
03 - In a large bowl, beat butter, granulated sugar, and brown sugar until creamy and fluffy, approximately 2-3 minutes.
04 - Add eggs one at a time, beating thoroughly after each addition. Mix in vanilla extract until incorporated.
05 - Gradually add dry ingredients to wet mixture, mixing on low speed until just combined. Avoid overmixing.
06 - Gently fold in mini marshmallows, crispy rice cereal, and white chocolate chips until evenly distributed throughout dough.
07 - Using a cookie scoop or spoon, drop rounded tablespoons of dough onto prepared baking sheets, spacing 2 inches apart to allow for spreading.
08 - Bake for 10-12 minutes, or until edges are lightly golden and centers appear set. Marshmallows should be toasted but not burnt.
09 - Let cookies rest on baking sheets for 5 minutes to set before transferring to wire rack. Cool completely before storing.