1. Place the butter in a light-colored saucepan over medium heat. Stir often until it melts, foams, and turns golden brown with nutty bits at the bottom. Remove from the heat and let it cool for 15 to 20 minutes.

2. Pour the cooled brown butter into a large bowl. Add the brown sugar and granulated sugar, then whisk until smooth. Mix in the eggs and vanilla extract until fully combined.

3. In a separate bowl, whisk together the flour, baking soda, baking powder, and salt. Add the dry ingredients to the wet ingredients and stir just until combined.

4. Fold in the crispy rice cereal, mini marshmallows, and marshmallow bits gently so the mixture stays light and textured.

5. Cover the dough and chill for 30 minutes.

6. Preheat the oven to 350°F and line baking sheets with parchment paper. Scoop the dough into medium portions and place them a few inches apart.

7. Bake for 10 to 12 minutes, until the edges are lightly golden and the centers still look slightly soft.

8. Let the cookies cool on the baking sheet for 5 minutes before transferring them to a wire rack.