In a small saucepan, heat the cream over medium heat, swirling the pan a few times, until bubbles start to form around the edge of the pan but the cream is not yet boiling, about 4 minutes. Remove from the heat, add the chocolate, and let sit for 30 seconds. Slowly whisk the mixture until the chocolate is completely melted and smooth. Let cool to room temperature before piping onto the meringues.
Make Ahead Tips
The ganache may be made up to 1 week ahead. Refrigerate in an airtight container and bring to room temperature before using.
Chocolate-Orange Ganache: Add 2 Tbs. finely grated orange zest (from 1 large orange) to the cream before heating. Heat the cream, remove it from the heat, and let sit for 1 hour. Strain through a fine sieve, pressing the zest with the back of the spoon. Reheat the cream to just under a boil and proceed as directed.
Photo: Colin Clark