Preheat oven to 350°F.
In a large mixing bowl with an electric mixer cream together butter and sugars. Scrape down sides of the bowl and mix in the eggs, one at a time.
Add vanilla and molasses and continue to beat together.
In another bowl whisk together the flour, baking soda and salt. Add flour mixture to the butter mixture and stir together until completely mixed together, but do not overmix.
Fold in the cereal, chocolate chips and marshmallows until fully incorporated. Refrigerate for 30 minutes to an hour.
Drop 2 ½ tablespoon sized dollops onto a baking sheet lined with parchment, about 1 inch apart from one another (the cookies will spread).
Bake for 10 to 12 minutes or until cookies have just begun to brown.
Allow cookies to cool for at least 5 minutes before serving. Store in an airtight container for up to 5 days.