Pour cream into a microwave-safe bowl; heat in microwave on high until very hot, 1 to 2 minutes. Add chocolate chips to heated cream; whisk until smooth.
Place chocolate-cream mixture in the freezer until ganache is cold and starting to thicken, stirring every 5 minutes, about 10 to 12 minutes.
Spoon ganache into a resealable plastic bag and refrigerate until completely cooled, 15 to 30 minutes.
Cut a corner from the plastic bag and pipe ganache.
