Biscotti means "twice cooked" in Italian. So these cookies you will bake, then slice and bake again until they are crispy and firm. They are best dunked in a cup of coffee or tea and a perfect afternoon snack!
Preheat the oven to 325°F. Butter 2 cookie sheets.
Place 1 cup of walnuts in the bowl of a food processor and blend until they are well ground.
With the second cup of walnuts, chop them into small pieces and set aside.
Beat the butter, sugar and banana on medium speed for 2 minutes until light and fluffy.
Add the eggs and vanilla and beat until well combined.
Sift flour with 1 cup ground walnuts, baking powder and salt. Gradually mix into the butter and banana mixture.
Stir the chopped walnuts and cocoa nibs (or chips) into the batter. (You can reserve 1/4 cup of the walnuts and pat them into the top of the biscotti if you want or mix them all in now.)
Divide the dough in half and pat into a 11 inch by 2 inch log with each half. Lay on one of the prepared cooking sheets.
Bake logs for 30 minutes, or until firm to the touch. Remove from the oven and let cool on a rack for 15 - 20 minutes.
Slice each log into 1-inch pieces - you should end up with 12 cookies from each log. Place on the second cookie sheet, with one of the cut sides down.
Bake for 10 minutes and then flip the cookies over to the other cut side and bake another 10 mintues.
Remove from the oven and place on a rack to cool. Then go dunk one in a hot cup of coffee and enjoy!