1. Preheat your oven to 350F/180C and line a baking sheet with parchment paper.
2. In a stand mixer with a paddle attachment, cream the butter, granulated sugar, and brown sugar on medium speed for 3–4 minutes.
3. Scrape down the sides, then add 2 eggs (one at a time) and the vanilla. Beat on medium until smooth, about 1–2 minutes.
4. In a separate bowl, whisk together the flour, espresso powder, baking powder, and salt.
5. Gradually mix the dry ingredients into the wet mixture on low speed until just combined.
6. Lightly flour your work surface and divide the dough into two portions.
7. Shape each into an 8×4½-inch rectangle (about ½ inch thick) on the prepared baking sheet. Brush the tops with a lightly beaten egg.
8. Bake for 25–30 minutes until lightly browned.
9. Let the biscotti cool for 15 minutes or until you can handle them. Keep the oven on.
10. Slice each slab into ¾-inch pieces.
11. Lay the slices, cut side up, on the baking sheet.
12. Bake for 10 minutes, flip, and bake another 10 minutes until golden and crisp. Cool completely on a wire rack.
13. Melt the bittersweet chocolate in a microwave-safe bowl at 50% power, stirring every 15 seconds (1–2 minutes).
14. Dip one end of each biscotti into the chocolate and place on a parchment-lined baking sheet.
15. Melt the white chocolate similarly and spoon it into a zip-top bag.
16. Snip off a small corner and drizzle over the dipped ends.
17. Let the chocolate set for at least an hour.
18. Store in an airtight container at room temperature for up to a week, or freeze for up to 3 months.

Need your biscotti stash to last?

1. Freeze them in an airtight container for easy coffee-pairing anytime over the next three months!