Starbucks Lemon-Tipped Biscotti

INGREDIENTS

• 6 tablespoons unsalted butter, at room temperature
• 1/2 cup granulated sugar
• 1 tablespoon grated lemon zest
• 2 large eggs
• 1 teaspoon vanilla extract
• 2 cups all-purpose flour
• 2 teaspoons baking powder
• 1/4 teaspoon salt
• 1 cup shelled pistachios, roasted and coarsely chopped
• 2 cups sifted powdered sugar
• 1 teaspoon grated lemon zest
• 1/4 cup lemon juice