In a large bowl, dissolve yeast in warm milk. Add the shortening, sugar, salt, eggs and 2 cups flour; beat on medium speed 3 minutes. Stir in remaining flour until smooth. Cover and let rise in a warm place until doubled, about 30 minutes.
Stir batter vigorously for 25 strokes (dough will be slightly sticky). Spoon into 12 greased muffin cups. Tap pans to settle the batter. Cover and let rise until batter reaches tops of cups, about 20 minutes. Meanwhile, preheat oven to 400°.
Bake 10-15 minutes or until golden brown. Brush with butter.