Using your hand, lightly knead the dough into a ball inside the bowl. Transfer the dough to your worktop to knead it if easier, but make sure not to overwork the pastry.
Turn the dough into a ball, roll it between two sheets of baking paper, about 3 mm (⅛") thick. Place on a flat tray and leave to rest in the fridge for an hour.
Let the ganache cool down just a little (for a few minutes), and pour it over the tartlet shells. Use a small spatula to spread it evenly if necessary.