In a large mixing bowl, beat together the butter and sugar, about 1 minute, until fluffy.
Add eggs, one at a time, mixing until just combined after each addition. Add peppermint extract and mix.
in a medium bowl, whisk together flour, baking powder, and salt.
Add flour mixture to the wet ingredients, and mix until just combined.
Add 1 cup of chocolate chips to the cookie dough and mix.
Line a baking sheet with parchment paper and spray the paper with non-stick cooking spray.
Divide dough into two equal amounts and form each half into a long skinny rectangle about 2-inches x 10-inches on the parchment paper.
Place in oven and bake for 30-35 min until light golden brown.
Carefully pull the parchment paper and cookies onto a cutting board. Slice cookie loaves in 1-inch thick pieces crosswise. (Starting at one of the shorter ends and slicing so you have cookie sticks.)
Place cookies back onto a cookie sheet cut side on the pan. Bake for 15 minutes.
Remove from oven and allow to cool for a few minutes on the baking sheet. Then transfer to a wire rack to cool completely.
Once cookies are cooled. melt remaining chocolate chips in a double boiler until smooth.
Dip half of each biscotti into the chocolate and then place on wax paper to let the chocolate set up. Store in an airtight container or enjoy once cooled.