1cup (130 grams) all-purpose flour
1/4 cup (25 grams) unsweetened cocoa powder (regular or Dutch-processed)
1/4 teaspoon salt
1/2cup (1 stick) (113 grams) unsaltedbutter, room temperature
1/2 cup (100 grams) granulated whitesugar
1/2 teaspoon pure vanilla extract
1 large egg yolk
3 ounces (90 grams) semi sweet chocolate, chopped
2 tablespoons (28 grams) unsalted butter, cut into pieces
1/3 cup (35 grams) lightly salted or unsalted roasted pistachios, coarsely choppedMethods:
Preheat oven to 350 degrees F (180 degrees C) with the rack in the center of the oven. Lightly butter, or spray with a non stick vegetable spray, an 8-9 inch (20-23 cm) tart pan with a removable bottom.
In a bowl, sift or whisk together the flour, cocoa powder, and salt.
Then, in the bowl of your electric mixer (or with a hand mixer), beat the butter and sugar until smooth (about 2 - 3 minutes). Beat in the vanilla extract and egg yolk. Scrape down the sides of the bowl as needed. Add the flour cocoa mixture to the butter and sugar mixture and beat just until a dough forms.
Press the shortbread dough in an even layer onto the bottom of the tart pan.Bake for about 20 - 25 minutes, or just until the shortbread no longer looks wet and is firm to the touch. Remove from oven and place on a wire rack.
Meanwhile, melt the chocolate and butter in a stainless steel bowl placed over a saucepan of simmering water. Immediately upon removing the shortbread from the oven, pour the warm chocolate glaze over the shortbread and, using an offset spatula or back of a spoon, evenly spread the glaze to within 1/2 inch (1 cm) of the edge of the shortbread. Sprinkle with the chopped pistachios and press them gently into the glaze. Let the chocolate shortbread cool completely then cut into 12-16 wedges.
Can be stored in a container at room temperature for several days.