Chocolate Shortbread

I'm trying out more chocolate recipes and recently I made this chocolate shortbread with a recipe from the Joy of Baking website. Chocolate Shortbread Recipe

Chocolate Shortbread: 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. In the bowl of your electric mixer (or with a hand mixer), beat the butter and sugar until smooth (1-2 minutes). Beat in the vanilla extract and egg yolk. Scrape down the sides of the bowl as needed. Add the flour 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 is set and no longer looks wet. Remove from oven and place on a wire rack. While the shortbread is baking, melt the chocolate and butter in a heatproof bowl, placed over a saucepan of simmering water (this can also be done in the microwave). 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 over the shortbread. Sprinkle with the chopped nuts and press them gently into the glaze. Let the chocolate shortbread cool completely then remove the sides of the tart pan and cut into 16 wedges. Can be stored in an airtight container at room temperature for several days or they can be frozen Makes 16 shortbread wedges. This is nice and buttery and not too sweet.  I think I'll make this to take down to the  Chocolate Festival in Robbins

Chocolate Shortbread: 1 cup (130 grams) all-purpose flour 1/4 cup (25 grams) unsweetened cocoa powder (regular or Dutch-processed) 1/4 teaspoon salt 1/2 cup (113 grams) unsalted butter, room temperature 1/2 cup (100 grams) granulated white sugar 1 teaspoon pure vanilla extract 1 large egg yolk Chocolate Glaze: 3 ounces (90 grams) semi sweet or bittersweet chocolate, chopped (or 1/2 cup (120 ml) semi sweet chocolate chips) 2 tablespoons (28 grams) unsalted butter, cut into pieces 1/3 cup (80 ml) salted or unsalted toasted nuts (pistachios, almonds, walnuts, pecans, or hazelnuts), coarsely chopped