-
1
Preheat oven to 350 degrees F (177 degrees C) and place rack in center of oven.
-
2
Line a baking sheet with parchment paper, and set aside.
-
3
In the bowl of your electric mixer (or with a hand mixer), cream the butter and sugar until light and fluffy (2-3 minutes).
-
4
Add the eggs and egg yolk, one at a time, mixing well after each addition.
-
5
Beat in the vanilla extract.
-
6
In a separate bowl, whisk together the flour, baking powder, salt, and cocoa powder.
-
7
Add to the butter mixture and beat until incorporated.
-
8
Stir in the chocolate/white chocolate chips.
-
9
Transfer the dough to a floured surface.
-
10
Form into a log 10 inches long.
-
11
Do this by rolling the dough back and forth into a cylinder shape with floured hands.
-
12
Transfer the log to the baking sheet, and pat to even the shape.
-
13
Bake until firm to the touch, about 25 - 30 minutes.
-
14
Remove from the oven, place on a wire rack, and let cool for about 10 minutes.
-
15
Using a long spatula transfer the logs to a cutting board.
-
16
Using a serrated knife, cut the logs into slices about 2/3 inch thick.
-
17
Arrange the slices on the baking sheet, cut side down, and bake about 8 - 10 minutes.
-
18
Turn the slices over and bake until crisp and dry, about 8 - 10 minutes longer.
-
19
Remove from oven and let cool on wire rack.
-
20
Optional Steps: Follow melting directions on dipping chocolate (or make your own), and use spatula/piping bag to drizzle chocolate over the tops of the biscotti.
