1. In a large bowl, whisk together the oil, sugars, eggs, and vanilla.
2. Add flour, cocoa, baking powder, baking soda, and salt. Mix until well combined. Stir in oats and marshmallows.
3. Refrigerate for a minimum of one hour.
4. Preheat oven to 350 degrees Fahrenheit (175 degrees Celsius). Line baking sheets with Gefen Parchment Paper.
5. Scoop dough onto prepared sheets, leaving two inches (five centimeters) between scoops. Top each scoop with a few extra marshmallows. Bake for 11 minutes.