In a large bowl, dissolve yeast in warm water. Add milk, sugar, shortening, lemon zest, salt, lemon juice, eggs and 1-1/2 cups flour. Beat on low speed for 30 seconds. Beat on high for 3 minutes. Stir in remaining flour (batter will be thick). Do not knead. Cover; let rise in a warm place until doubled, about 1 hour.
Stir dough down. Fill greased muffin cups half full. Cover and let rise until doubled, about 30 minutes.
Combine sugar and cinnamon; sprinkle over the dough. Bake at 375° for 15-20 minutes or until golden brown. Remove from pans to wire racks. Serve warm.