In the bowl of a stand mixer, combine 1 cup all-purpose flour, whole wheat flour, yeast, sugar, and salt. Whisk to combine.

In a small saucepan, heat water and shortening until 120 to 130 degrees F. (Shortening will not melt)

Add warm liquid to the bowl and stir to combine. Place bowl on stand mixer with the flat beater. Mix on medium-low speed for 2 minutes.

Switch flat beater to dough hook. Turn mixer to speed recommended for using the dough hook. Gradually add walnuts and enough remaining flour to make a firm dough.

Knead with the dough hook for 4 to 5 minutes. While dough is kneading, grease a large bowl.

Turn dough out on a lightly floured surface and hand knead a few times until the surface is smooth and elastic.

Place dough in the greased bowl and turn to coat surface. Loosely cover with plastic wrap or tea towel.

Let rise in a warm place (72 - 75 degrees F) until doubled, about 1 hour.

While the dough is rising, grease two loaf pans (9- X 5- or 8- X 4-inch).

Punch down dough and divide in half.

Roll or pat each half to a 14- X 7-inch rectangle. Start with the shorter side and roll up tightly while pressing dough into roll with each turn. Pinch edge and ends to seal.

Place rolled dough in bread pans. Cover with a tea towel and let rise until double, about 1 hour.

Pre-heat oven to 375 degrees F while bread is on the second rise.

Bake loaves for 35 to 40 minutes, until loaves sound hollow when tapped. Rotate loaves half way through baking for even browning.

Remove loaves from pans and cool completely on a wire rack.