Add the flour mixture to the liquid mixture gradually, beating in until well combined. Add finely chopped walnuts.
Dump all the dough on a flat surface, and divide in half (If you find that the dough is still soft, just add some all-purpose flour until it's mouldable, but keep in mind you don't want a very stiff dough). Using well-oiled hands, roll each ball back and forth with your palms to form a log, about 11 inches long. Repeat for the remaining dough.
Place both logs as far apart as possible on an oiled baking sheet. Press down slightly on the logs to flatten them a little.
Bake in a preheated 375-degree oven until the logs are beginning to set, around 25 minutes.
Remove the baking sheet to a rack and when the logs are cool enough to handle, place one on a cutting board. Using a serrated knife and a sawing motion, cut into 1/2-inch slices.
Return the biscotti to a baking sheet and bake for 10 minutes. Flip over and bake the other side for another 10 minutes.