Directions

1. Preheat oven to 350 degrees. In a large bowl, whisk together flour, 3/4 cup sugar, baking powder, and salt; stir in pistachios and chocolate. In a small bowl, whisk together eggs, butter, vanilla, and cocoa. Add egg mixture to flour mixture and stir until combined (dough will be stiff, so mix with hands if necessary).
2. Line a rimmed baking sheet with parchment and sprinkle with 2 tablespoons sugar. Divide dough in half and place on sheet. Shape into two 2 1/2-by-12-inch logs and sprinkle top of each with 1 tablespoon sugar. Bake until risen and firm, 15 to 20 minutes. Let logs cool completely on sheet, about 30 minutes.
3. Reduce oven to 300 degrees. Using a serrated knife, cut logs crosswise into 1/2-inch-thick slices. Arrange slices in a single layer on baking sheets. Bake until biscotti are dry, 15 to 20 minutes. Transfer to a wire rack to cool completely. (To store, keep in an airtight container at room temperature, up to 1 week.)