01 - Preheat oven to 350°F. Line baking sheets with parchment paper.
02 - Whisk together flour, baking soda, and salt in a medium bowl.
03 - Beat butter, granulated sugar, and brown sugar in a large bowl until creamy and fluffy.
04 - Add eggs one at a time, beating well after each addition. Mix in vanilla extract.
05 - Gradually add dry ingredients to wet ingredients, mixing until just combined.
06 - Fold in mini marshmallows, crispy rice cereal, and white chocolate chips if using.
07 - Drop dough onto prepared baking sheets using a cookie scoop, spacing 2 inches apart.
08 - Bake for 10-12 minutes until edges are golden and centers are just set.
09 - Let cookies cool on trays for 5 minutes before transferring to a wire rack.