Step 1

Preheat oven to 350°F, and line a baking sheet with parchment paper. Whisk together flour, baking powder, and salt in a small bowl.

Step 2

Beat softened butter and sugar in a stand mixer fitted with a paddle attachment on medium speed until light and fluffy, about 3 minutes. Add eggs, 1 at a time, beating until blended after each addition. Add vanilla, bourbon, and grated orange zest, and continue beating until incorporated. (Mixture may separate slightly, which is okay.)

Step 3

Reduce speed to medium-low, and gradually add flour mixture, one-third at a time. Beat until well blended. Fold in chopped almonds using a rubber spatula. With floured hands, scoop dough onto a lightly floured surface. (Dough will be very sticky.)

Step 4

Roll dough into a 15-inch-long log. Carefully transfer log to prepared baking sheet, and gently press top to shape log into a ½-inch-thick rectangle (about 4 inches wide).

Step 5

Bake in preheated oven until golden and puffy, about 25 to 30 minutes, rotating baking sheet from front to back halfway through bake time. Transfer baked rectangle to a wire rack, and let cool 15 minutes. Reserve parchment paper-lined baking sheet.

Step 6

With a sharp serrated knife, cut rectangle crosswise into ¾-inch-thick slices. Arrange cookies, standing upright (not on cut sides), on reserved baking sheet, and return to oven. Bake at 350°F until lightly dried, deep golden, and crisp on the outside, about 15 to 20 minutes. Transfer cookies to a wire rack, and cool completely, about 30 minutes. Cover baking sheet with a new sheet of parchment paper.

Step 7

Arrange biscotti, cut side up, on prepared baking sheet. Melt white chocolate chips according to package directions, and stir in oil until thoroughly combined. Drizzle melted white chocolate mixture over biscotti. Let stand until chocolate sets, about 30 minutes. Store in an airtight container at room temperature.