VANILLA-CITRUS BISCOTTI

Steps:

• Make the cookies: Preheat the oven to 350 degrees F. Line a baking sheet with parchment paper. Whisk the flour, baking powder, salt and baking soda in a medium bowl. Melt the butter in a large microwave-safe bowl in the microwave. Whisk in the granulated sugar and eggs until smooth; whisk in the grapefruit and lemon zest. Stir in the flour mixture with a rubber spatula until just combined, then stir in the orange peel.
• Divide the dough in half. Shape each piece into an 8-inch log about 2 inches wide on the prepared pan. Bake until golden, about 25 minutes. Let cool 10 minutes on the pan.
• Reduce the oven temperature to 325 degrees F. Slice the logs crosswise 1/2 inch thick. Arrange the slices cut-side down on the same pan. Bake, rotating the pan once, until the cookies are dry, 30 to 35 minutes. Let cool completely on the pan.
• Make the glaze: Heat the butter and vanilla pod and seeds in a skillet over medium heat until the butter sizzles, 1 to 2 minutes. Let cool slightly, then strain into a bowl. Whisk in the confectioners' sugar and 3 tablespoons heavy cream, thinning with the remaining 1 tablespoon cream if needed. Transfer to a small resealable plastic bag, snip a corner and pipe on the biscotti. Sprinkle with nonpareils. Let set, about 45 minutes.