1. Preheat oven to 350°F (175°C) and line a baking sheet with parchment paper.

2. In a large bowl, cream together softened butter and sugar until light and fluffy.

3. Beat in eggs one at a time, then stir in sourdough starter and vanilla extract.

4. Whisk flour, baking powder, and salt in a separate bowl, then gradually add to wet ingredients until dough forms.

5. Fold in dried cherries and orange zest until evenly distributed.

6. Divide dough into two equal portions and shape each into a 10–12 inch log, 2–3 inches wide.

7. Place logs on prepared baking sheet and bake for 25–30 minutes until firm and lightly golden.

8. Cool logs on the baking sheet for 10–15 minutes until they are warm to the touch.

9. Slice logs diagonally into 3/4-inch slices using a serrated knife.

10. Reduce oven to 325°F (160°C) and arrange slices cut side up on the baking sheet.

11. Bake for 10–12 minutes on one side, flip, then bake 8–10 minutes more until golden and crisp.

12. Transfer biscotti to a cooling rack to firm up before serving or storing.