Warm the milk, sugar, the 1/2
cup butter and shortening and salt together in a small, heavy pan over low heat,
just until the butter and shortening melt. Set the pan aside to cool to lukewarm.
Add the liquid to the yeast, and let the mixture sit for 5 minutes.
Mix in the eggs and potatoes. Stir in as much of the flour as is needed to form
a soft dough.
Cover the bowl with a towel, and let the dough rise until it has nearly doubled
in size, about 1 1/2 to 2 hours.
Sprinkle a counter with some of the remaining flour, and knead the dough for
a couple of minutes to make it smooth and elastic. Add in a little flour, if needed,
to make the dough more workable. Roll the dough out to a 1/2- to 1/2-inch thickness.
Cut it into rounds with a 3-inch biscuit cutter. Brush half of each roll's top
with melted butter and fold the unbuttered half over it, so that the upper half
extends about 1/2 inch beyond the lower half. Arrange the rolls on a greased baking
sheet with the rounded side of each roll just touching the flat side of the roll
next to it. Allow the rolls to sit, covered, for 1 hour or until they are doubled
Heat oven to 400 degrees F.
Bake rolls for 10 minutes.
Reduce the temperature to 350 degrees F and bake rolls an additional 10 to
12 minutes, or until they are nicely browned.