1 cup lightly toasted hazelnuts (with skins rubbed off)
Method
To make the tart pastry, preheat the oven to 200 C (400 F) and get out a muffin pan.
Place the butter, water, oil, sugar and salt in an overproof bowl.
Put the bowl in the oven for about 15 minutes, until the butter is melted, bubbling, and just beginning to brown around the edges.
Carefully 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 a tablespoon of dough into one muffin hole, and press it into the base and up the sides using your fingers. Repeat until all the dough has been used.
Prick the dough with a fork once or twice.
Bake for 8 - 12 minutes, until the pastry is golden brown all over.
Remove from the oven and set aside to cool.
Meanwhile, reduce the oven temperature to 160 C (325 F) and make the filling.
Place chocolate in a heatproof bowl and set aside.
Put the butter, hazelnut liquor (or coffee) and half the sugar (1/3 cup) in a small saucepan over a medium heat. Stir until the butter melts and the sugar dissolves, then pour over the chocolate. Stir until the chocolate melts.
Using an electric mixer, whip the eggs, half the sugar (1/3 cup) and salt until the mixture is thick, pale, and falls off the whisk in a ribbon.
Whisk a third of the egg mixture into the chocolate mixture to lighten it, then fold the rest in gently, until combined.
Pour the filling into the tart shells until it almost reaches the top.
Allow to cool completely before serving. Makes 12 tarts.
Happy baking!
NOTE: When making the tart at work, I bake with a cold filling from the fridge and the tarts turn out differently - covered in hazelnuts. At home I baked these with fresh, runny filling, and found that the hazelnuts sunk. You may want to refrigerate your filled tarts for an hour or so before topping with hazelnuts and baking.
Recipe by Butter Baking at https://www.butterbaking.com/2013/11/13/chocolate-hazelnut-tarts/