Preheat your oven to 175 degrees Celsius / 347 degrees Fahrenheit.
In a bowl, mix all the crust ingredients and then transfer to a pie dish, pressing the crust firmly with a spoon or your hands. Bake for 10-12 minutes until it’s firm and a little browned. Set aside while you make the filling.
Place the dark chocolate in a large heat-proof bowl. In a saucepan, heat milk until it’s steaming but not boiling. Pour the heated milk into the chocolate. Let it sit for 3 minutes and then start stirring with a spoon or spatula. Add the vanilla, mint essence, espresso powder and salt. Whisk until all the dark chocolate is melted and the mixture is smooth and glossy.
Pour the filling into the crust. Chill for 1-2 hours until set. Top with your favorite fresh berries. To serve, dip a knife into hot water and wipe with a towel so it slices cleanly into the tart. Store the tart in the fridge for up to 4 days or in the freezer for longer.