In the bowl of a stand mixer fitted with the paddle attachment, add the butter and sugar and cream together until light and well mixed.
Add the eggs and vanilla and mix again.
Add the starter and mix until well combined.
Turn the mixer on slow and add the flour and salt.
Add the chocolate chips and mix until just combined.
Line a baking sheet with parchment paper. Shape the dough into two logs on the baking sheet. Place the baking sheet in the refrigerator for 30 minutes.
Preheat the oven to 350 degrees.
Place the baking sheet in the oven for 30 minutes, or until the logs or slightly browned.
Take the baking sheet out of the oven and allow the logs to cool completely.
Once cooled, cut the logs with a serrated knife on a bias. Place the slices on a baking sheet, cut side up. Bake them for 15 more minutes to dry out the cookie and crisp the biscotti.
They are done when they are slightly brown. Allow the biscotti to cool on a cooling rack.