Preheat Oven to 350 degrees F
Line a large baking sheet with parchment paper, or do as I did and use these wonderful Baking Mats. Blend the flour and baking powder in a medium bowl.
Using an electric mixer, beat the butter, sugar, zest, and salt in a large bowl until blended. Beat in the eggs 1 at a time. Add the flour mixture and continue beating until blended. Stir in the two types of chocolate morsels.
Form the dough into approximately a 12 inch long, 3 inch wide log on the parchment or baking mat. Bake until golden, about 30 – 40 minutes.
Cool for 30 minutes.
On a cutting board, with a serrated knife, cut the log on a diagonal into 1/2 to 3/4 inch slices. Arrange the Biscotti, cut side down, on the parchment or baking mat. Bake the Biscotti until they are golden, about 15 minutes. Transfer the Biscotti to a rack and cool completely.
You can make these Biscotti ahead of time. Just be sure to store them in an airtight container , or wrap them in saran wrap and then freeze in plastic freezer bags.