In a stand mixer fitted with the paddle attachment, place 5 pounds cake mix, 1 pound 8oz softened butter, and 8oz bread flour in the bowl and mix on 1st speed for 2 minutes. Scrape the bowl and slowly add 8oz water and 8oz whole eggs. Scrape the bowl and mix on 2nd speed for 3 minutes. Add 1 pound 3oz white chocolate chips and mix on low speed for 30 seconds.
Scale dough into 2 pound duffs, shape into a rectangle 4 inches wide and 12 inches long, and 1 inch thick. Bake at 350F for 30 minutes or until hte internal temperature is 200F. Let cool completely and then slice into 1 inch thich slices. Bake at 325F for 45 minutes or until biscotti is crunchy. Let cool completely, garnish with drizzled white chocolate if desired.