1. Preheat the oven to 350 F and line a large baking sheet with parchment paper or a silicone baking sheet. Set aside.
2. In a large bowl, whisk together the flour, baking powder and salt. Set aside.
3. In a small bowl, combine the lemon zest, sugar and poppy seeds. Massage the ingredients together with your fingers until thoroughly combined. Add the egg, vanilla extract and lemon juice and whisk until combined.
4. Add the wet ingredients to the flour mixture, and stir together until a soft dough forms. The dough will be dry and flaky, so use your hands to knead the mixture until there are no loose flakes.
5. Separate the dough into two balls, and on a floured surface, flatten each ball into a long log about 9″ long and 2 1/2″ wide. Place the logs onto the prepared baking sheet, a few inches apart, and bake for 12 minutes.
6. Remove from the oven, and allow the logs to cool 10 minutes until transferring them to a cutting board and cutting them on the diagonal, into 1/2″ pieces. The sharper the angle that you hold your knife, the longer your biscotti will be.
7. Reduce the oven temperature to 300 F. Place the cut biscotti on its side onto the baking sheet, and bake for another 15 minutes. Allow the biscotti to cool completely on the baking sheet.
8. Combine the coconut oil and white chocolate together in a microwave safe bowl (alternatively, use a double boiler) and melt the chocolate at high heat in 30 second increments, until smooth.
9. Transfer the chocolate to a Ziploc bag and cut the tip of the bag off, drizzling the chocolate all over the biscotti. Allow the chocolate to harden before storing.

Biscotti will keep at room temperature, in an airtight container for up to 3 weeks, or up to 3 months in the freezer.