Combine 1 cup flour, sugar, undissolved yeast and salt in a large mixing bowl. Heat milk, water and shortening until very warm (120° to130°F). Gradually add to dry ingredients. Beat 2 minutes at medium speed of electric mixer, scraping bowl occasionally. Stir in mashed potato, eggs and 1 cup flour; beat 2 minutes at high speed, scraping bowl occasionally. Stir in remaining flour to make a stiff batter. Cover loosely with plastic wrap; refrigerate 2 to 24 hours.
Punch dough down; divide into 2 equal portions. Roll each half to 12 x 7-inch rectangle. Beginning at short end of each rectangle, roll up tightly as for jelly roll. Pinch seam and ends to seal. Place seams side down, in greased 8-1/2 x 4-1/2 inch loaf pans. Cover; let rise in warm, draft-free place until doubled in size, about 1 hour.
Bake at 375°F for 30 to 35 minutes or until done. Remove from pans; cool on wire rack.
To make rolls: Divide dough into 36 equal pieces; shape into smooth balls. Place balls, about 2-inches apart, on large greased baking sheets. Cover; let rise in warm, draft-free place until doubled in size, about 1 hour. Bake at 400°F for 13 to 15 minutes or until done. Remove from sheets; cool on wire racks.
* Instant mashed potatoes, made according to package directions can be used.