Position knife blade in food processor bowl; add raspberries. Process about 1 minute or until smooth. Strain and discard seeds. Set aside.
Combine sugar and cornstarch in a small saucepan. Add milk; bring to a boil, and cook 1 minute, stirring constantly. Remove from heat. Stir in raspberry puree and corn syrup. Cool completely. Combine raspberry mixture and yogurt in a bowl; stir well. Cover and chill 8 hours.
Pour raspberry mixture into a freezer can of a 1-quart hand-turned or 1/2-gallon electric freezer. Freeze according to manufacturer's instructions. Allow to ripen 1 hour in freezer can.