Potato Bread

In a saucepan, cook potato in 1 1/2 cups water until tender. Cool to lukewarm. Set aside 1/2 cup of the cooking liquid. Mash potato in remaining liquid, adding water if needed, to make 2 cups potato mixture. Proof yeast in remaining liquid. Combine potato mixture, yeast mixture, sugar, shortening and 1 Tbsp salt; mix well. Stir in 2 cups of the flour' beat well. Let rise in a warm place until double (about 45 minutes). Stir down and add enough of the remaining flour to make a moderately stiff dough. Knead until smooth and elastic (about 10 min.). Shape into a ball and place in a greased bowl, turning once to grease ball. Cover and let rise until double (about 45 min.). Punch down and turn out onto a floured surface. Divide in half. Cover and let rest 10 minutes. Shape into loaves and put in two greased 8.5x4.5x2.5-inch loaf pans. Cover and let rise until almost doubled (about 45 min.). If desired, brush tops with milk and dust with flour. Bake at 375F for 40 to 45 minutes. Remove from pans and cool.