For the tart shell
- Preheat oven to 160* C (320* F) Fan.
- Beat the flour, icing sugar, cocoa powder, butter and salt in a mixer until all of the ingredients are completely combined.
- Add the egg, at room temperature along with the cold water and beat.
- When the dough comes together nicely, transfer to a prepared 25 cm springform pan. Slice off the ends that are overhanging from the pan.
- Cover with 2 pieces of plastic wrap, in a crisscross manner. Add cooking weights or beans so that the dough doesn’t rise. Fold the ends of the wrap inward.
- Bake for 30 minutes. Remove from oven, remove weights and wrap and bake for another 15 minutes.
For the white chocolate buttercream
- Chop the white couverture in to pieces and place in a bowl. Place over a saucepan with boiling water to create a bain marie. Stir with a spatula until it melts and spread in a pan. Set it aside to cool.
- In a mixer’s bowl, add the chilled butter, cut into small cubes along with the icing sugar and beat until the mixture is light and fluffy.
- When ready, add the white chocolate from the pan and beat again until fluffy.
- Transfer buttercream to a pastry bag and decorate surface of tart by making small flower shapes (rosettes).
For the ganache
- In a saucepan, add the heavy cream and place over medium heat. Bring to a boil.
- In a bowl, add the couverture cut in to small pieces and the hot heavy cream. Let the mixture sit for a little so that the chocolate softens and mix until it melts completely.
- Add the coffee liqueur and mix.
- Pour the ganache over the tart and buttercream. Refrigerate for 2-3 hours to chill.
- When ready, remove from refrigerator and allow to cool.
- Serve with fresh mint.