These two-tone cookies are great fun for kids to make. They'll love squishing the cookie dough together to make each marble. Cream cheese gives these cookies an added richness. Just make sure both the butter and cream cheese are at room temperature before you start so that they'll incorporate fully into the dough. The food colouring is optional - omit it if you like or add more if you prefer a more vibrant green.
Cookies keep up to 3 days in an airtight container at room temperature, or up to 3 months frozen.