Ingredients

• 2 cups all purpose flour
• 1 cup (packed) golden brown sugar
• 3 tablespoons cornstarch
• 1 tablespoon plus 1 teaspoon instant espresso powder
• 3/4 teaspoon salt
• 1 cup (2 sticks) chilled unsalted butter, cut into 1/2-inch pieces
• 1 teaspoon vanilla extract
• 2/3 cup hazelnuts, toasted, husked, coarsely chopped
• 2 tablespoons hot water
• 2 ounces semisweet chocolate, chopped

Instructions

1. Preheat oven to 350°F. Blend flour, brown sugar, cornstarch, 1 tablespoon espresso powder and salt in processor. Add butter and vanilla. Using on/off turns, process until mixture resembles coarse meal. Add nuts; blend until finely chopped. Transfer dough to floured work surface. Knead just until dough comes together.
2. Divide dough in half. Press each half into 9-inch-diameter tart pan with removable bottom. Bake until deep golden brown, about 25 minutes. Transfer shortbread to rack; cool 2 minutes. Remove pan sides.
3. Cut each shortbread round into 24 wedges. Cool completely.
4. Mix 2 tablespoons hot water and remaining 1 teaspoon espresso powder in small saucepan. Add chocolate. Stir over medium-low heat until chocolate is smooth. Remove from heat. Cool slightly. Drizzle chocolate mixture over cookies. Let stand until chocolate sets. (Can be prepared ahead. Store in airtight container at room temperature up to 1 week, or freeze up to 1 month.)