Modified from Food Network
1 1/4 cup butter (this is 2 sticks plus 4 tbsp., which is half a stick more...this is listed as unsalted, which I did use this time as I had it...if I didn't, I'd just adjust)
5 cups flour
5 1/2 tsp baking powder
1 tsp salt
6 eggs (they said large, I used extra large)
2 1/2 cups sugar
4 tsp vanilla
1 cup smooth peanut butter
2 1/2 cups dry roasted peanuts
1 pkg (10 oz) dark chocolate chips (they said 12 oz or 2 1/2 cups, but this is the typical package and just what I used here)
Preheat oven to 350. Line baking sheets with parchment paper. Melt butter over medium heat. (This says to brown butter, I did let it cook a bit, but that was it). Let cool slightly.
Whisk flour, baking powder and salt in a large bowl. Beat eggs in mixer until light and pale yellow. Add in sugar while beating. Then slowly add in cooled butter and vanilla until evenly mixed. Add in peanut butter and mix until combined.
While mixing slowly, add the dry ingredients in several parts to wet until just absorbed. Fold in peanuts and dark chocolate chips.
Divide dough into 6 sections. Shape the dough with slightly wet hands into logs about 2 inches wide and 15 inches long. Bake until set and brown around the edges, about 25-30 minutes. Cool for about 10 minutes. Lower oven temperature to 325. Carefully transfer to the log to a cutting board. Cut logs with a serrated knife into 1/2 inch thick cookies. Place cookies side down on the baking sheets. Bake until crisp, about 8 minutes. Flip the cookies over and bake until golden brown, about 8 minutes more. Cool biscotti on the baking sheet.
Makes about 10 dozen cookies.