First dissolve the gelatin in cold water. Meanwhile pour the double cream into a saucepan. After that cut the vanilla pod in half, scrap out the seeds and add it to the cream. Now bring this to a boil.
Once it’s boiling turn off the heat and dissolve the gelatin. Then remove the vanilla pod. Now transfer white chocolate and the mascarpone in a measuring jar. Then pour the hot vanilla cream on the white chocolate and mascarpone and emulsify it with a hand blender. Then let it set in your fridge for at least 6 hours.
After that transfer the mascarpone ganache into a stand mixer bowl and whisk it till a medium stiff peak starts to form. This is going to take around 3 minutes. Don’t over whisk it otherwise the ganache will separate. Then it’s ready to be used!
Try to pipe it as soon as possible for the best result. It’s still great later on, but the appearance will change a little bit once it’s set again.