Is It Kosher? Marshmallows are kosher only when they carry a reliable hechsher, and many common brands do not. The reason is gelatin, which is usually made from animal sources that are not kosher. Certified marshmallows, fish-gelatin versions, and vegan options are the ways around it.
Is It Kosher? Yes, Oreos sold in the United States are kosher. Every standard variety carries OU-D certification from the Orthodox Union, meaning they are certified kosher dairy. Outside the US the answer gets more complicated, and this guide walks through exactly what to check on the package.