A good way to remove chocolate ice cream stains is to use some soda water or some baking soda and vinegar and add the solution to the chocolate ice cream stain.
Allow the vinegar and baking soda or the soda water to sit on the stain for awhile.
You should let it sit for around 20 minutes and then add some more and use a toothbrush or other brush and scrub the stain out.
Then use some stain remover solution to clean the rest of the stain out if there is any leftover stain.
Then run the clothes through the washing machine after that.
Tide stain release will also help remove more stubborn chocolate ice cream stains and other stains from clothing.