Tart pastry: preheat oven to 200°C and lightly butter a 25cm tart pan with removable bottom. Place the Ladismitter Cultured Butter, water, oil, sugar and salt in an ovenproof bowl. Put the bowl in the oven until the Ladismitter Cultured Butter is melted, bubbling, and just beginning to brown around the edges (15 minutes). Remove the bowl from the oven and dump in the flour. Stir quickly, until the dough comes together and pulls away from the side of the dish. Put the dough into the base of the tart pan.
Press the dough around the base of the pan with a spatula, wait to cool off. Prick the dough all over with a fork and place the tart pan on a baking tray. Bake for 15 – 20 minutes, until the pastry is golden brown all over.
Tart filling: reduce the oven to 180 °C. Place the brown sugar, glucose and Ladismitter Cultured Butter in a medium saucepan over a low heat. Cook, stirring occasionally, until the Ladismitter Cultured Butter is melted and the ingredients are combined. Turn off the heat, add the chopped chocolate and allow to sit, without stirring, for 2 – 3 minutes.
In the meantime, whisk together the eggs, coffee, salt and vanilla in a large bowl. Scatter the nuts evenly over the base of the tart pastry. Now stir the chocolate mixture until it is well combined, and pour half of it into the eggs. Whisk until it is well combined, then add the remaining half and whisk again. Pour the chocolate filling over the nuts.
Place the tart back in the oven and bake for about 30 minutes.