Combine cherries, water, lemon juice and sugar in a saucepan and bring a boil. Reduce to a simmer for about 30 minutes. Stir and mash the cherries occasionally with a spoon. Once you have a thicker sauce, remove from heat.
Heat cream until warm and steaming, then whisk in the gelatin mass until completely dissolved.
475 grams heavy cream
Pour the warm cream over the chocolate and stir until all the chocolate is melted.
Let the mixture cool to room temp and stir in the cherry puree.
240 grams cherry puree
Blend with an immersion blender until smooth. Place plastic film directly onto the ganache and refrigerate for a minimum of 12 hours to allow the chocolate to re-crystallize.
The next day, scoop cold ganache into the bowl of a stand mixer. Using the whisk attachment to whip until thick and fluffy medium peaks. About 2-3 minutes on medium speed. Careful not to over whip, or the mixture separate.
Use immediately to pipe as a topping or filling.
Notes
Storage: Keep refrigerated. Treat ganache like a stabilized whipped cream. It is best stored in the fridge, but since it's stabilized with gelatin it will hold its shape at room temp for serving.
Piping: If you see the whipped ganache getting soft while decorating (usually due to a warm hand or hot kitchen), just place it back in the fridge for about 10-15 minutes then pipe again.