Finely chop the dark chocolate and place it in a bowl.
200 grams Dark chocolate
Add the cream, hot chocolate powder, and butter into a saucepan. Place over medium heat and stir continuously until piping hot but not boiling.
2 tablespoons Whittard Tonka Bean Flavoured Hot Chocolate, 200 millilitres Double cream, 50 grams Unsalted butter
Pour the mixture over the chopped chocolate and cover the bowl with an upside plate to trap the heat inside. Leave for 1 minute.
Stir until the ganache looks smooth, combined, and glossy. Looking split or slimy? Don't worry, we can fix it (see note 1 below).
Pour the ganache into the pastry case and smooth it out. Lightly tap the tin to remove the air bubbles.
Chill in the fridge for at least 1 hour or until the filling is set.