When bowl mixture has cooled, stir in yeast. Gradually beat in whole wheat flour, 2 cups all-purpose flour, gluten, salt and walnuts on low speed until combined. Beat 3 minutes on medium speed. If dough is too wet, use additional ¼ cup all-purpose flour to make a soft dough. Knead with dough hook 8 to 10 minutes or by hand until smooth and elastic.