In a small bowl, dissolve yeast in warm water. Add 1-1/2 cups flour; beat until smooth. Cover and let rise in a warm place for 30 minutes.
In another bowl, cream shortening and sugar. Add eggs, one at a time, beating well after each addition. Beat in molasses until smooth. Add the yeast mixture. Combine cinnamon, salt, baking soda, ginger and remaining flour; gradually add to egg mixture. Stir in nuts.
Fill greased or paper-lined muffin cups two-thirds full. Bake at 350° for 20-25 minutes or until a toothpick comes out clean. Cool for 5 minutes before removing from pans to wire racks.