Mix the cream with the espresso and bring this to a simmer.
Now transfer the white chocolate into a bowl and once the espresso mixture is simmering pour it on the chocolate. Blend this till smooth.
Then add the butter and blend it once more. Keep the blender at the bottom of the bowl to prevent air from mixing with the ganache. Then cover the ganache and let it set in your fridge.
Once it’s set transfer it into a piping bag that’s fitted with a round nozzle and keep it in your fridge for later.