Process raspberries, yogurt, sugar and vanilla in a food processor or blender until smooth.

Pour mixture into a small ice cream freezer and freeze according to directions. Add chocolate chips in the last five minutes of freezing. Transfer into an airtight container and freeze until ready to serve.

If you don't have an ice cream maker, pour the mixture into a 9 x 13 pan and freeze, stirring every 2 hours. When the mixture is semi-solid in the center, transfer it into a food processor and process until smooth. Dump into an airtight container, stir in the chocolate chips, and freeze until serving time.