Once the tart base is set, gently pour the cooled dark chocolate ganache into the tart pan.
Store in fridge for 20 minutes.
After 20 minutes, remove and add in the blueberries. The texture of the ganache should be slightly set, allowing the blueberries to stick (but not sink) into the ganache. Once all the blueberries are placed as you wish, cover lightly with cling wrap and return the tart to the fridge for at least 2 hours (or until set).
Before serving, garnish tart with dried edible flowers and/or cacao nibs for the added spring time look. Remove from tart pan and serve chilled on its own or a dollop of freshly whipped cream.