adapted from Alice Medrich’s Pure Dessert
makes one 9 1/2 in tart or (6) 3 1/2 in tarts
http://dessertfirstgirl.com/2007/09/bittersweet-cit.html
Crust
8 tablespoons unsalted butter, melted
1/4 cup sugar
3/4 teaspoon vanilla extract
1/8 teaspoon salt
1 cup (4 1/2 oz) flour
Filling
8 oz semisweet chocolate (62% preferred, I used Guittard 61%)
5 tablespoons butter
1/2 teaspoon grated blood (or regular) orange zest
1/2 teaspoon grated pink grapefruit zest
1 large egg yolk, room temperature
1/4 cup boiling water
For the crust: Preheat the oven to 350 degrees F. Combine the melted butter, sugar, vanilla, and salt in a bowl and mix together with a wooden spoon.
Add in the flour and mix until combined. You can let the dough sit for a few minutes to firm up if it seems too soft to manipulate.
Grease the bottom and sides of your tart pan(s) – I suggest ones with removable bottoms to make it easier to remove the tarts after baking.
Press the tart dough into the bottom and sides of the tart pans, taking care to spread the dough as evenly and thinly as possible (this is not difficult but may take some time and patience.)
Bake the tart shells in the oven for about 20 minutes or until the shells appear golden brown and firm. Remove and let cool completely on a wire rack.
For the filling: Combine the chocolate, butter, and citrus zest in a bowl and set over a saucepan of simmering water to create a bain-marie. Stir frequently to ensure the chocolate and butter melt together evenly. When the mixture is completely melted, take off the heat and set aside.
Place the egg yolk in a small bowl and slowly whisk in the boiling water, taking care not to cook the egg. Place the bowl over the simmering water and whisk the egg mixture continually until it reaches a temperature of 160 degrees F.
Pour the egg through a strainer into the chocolate mixture and stir gently to combine – try to avoid creating air bubbles in the mixture.
Pour the filling into the tart shells and spread evenly. Place the tarts in a covered container and chill in the refrigerator for at least 3 to 4 hours to set the filling.
When you ready to serve the tarts, take them out of the refrigerator about half an hour beforehand to let it soften and regain the shine on its surface.