Make the pastry as per the chocolate pastry recipe (linked in recipe notes below). Use a 24cm/9.5 inch fluted tart tin.
Once the pastry has been blind baked, allow it to cool.
Very finely chop your chocolate and place into a medium heatproof bowl.
Add the cream, sugar, salt and optional vanilla to a small pot over a medium heat. Cook until the sugar has dissolved and the cream is bubbling, then pour over the cream.
Cover and allow to sit for 1 minute before stirring. I like to put my butter in the hot saucepan while I wait to give it a chance to start melting. I have had a few instances where the butter hasn’t properly melted into the ganache which isn’t cute.
Stir very thoroughly to ensure the butter is fully incorporated. I have seen some people suggest using an immersion blender to be certain the mixture has emulsified.
Pour the chocolate ganache into the cooled tart crust. Shake it around and gently drop the tin on the counter a few times to smooth the ganache out and encourage out any air bubbles. Once it has cooled a little, place it into the fridge for at least 1 hour to allow the ganache to set. I highly recommend making it the day before if you are making this for an event.
If you are using the raspberries, press them into the tart open side down about 45 minutes after pouring the ganache and allow it to cool on the bench instead of in the fridge. The ganache should be quite firm but still soft enough to adhere the raspberries. I find it easiest to start with the outside circle and work my way inwards.
You can decorate the tart with whatever else you like, too. Leftovers keep well in an airtight container in the fridge for a number of days. They can also be frozen and defrosted.