Stir together the yeast, sugar and warm water in a large bowl and allow the mixture to rest and become bubbly for about 5 minutes.

Add the milk, butter, mashed potatoes and salt. Mix in enough flour to form a firm dough (you may need slightly less or more than the 5 cups listed).

Turn the dough out onto a lightly floured surface and knead until smooth and elastic, about 6-8 minutes.

Form the kneaded dough into a ball and place into a large, greased bowl. Cover with plastic wrap or a kitchen towel and let rise in a warm place until doubled, about 1 hour.

Gently punch down the dough and then turn it onto a floured surface. Shape into two round loaves and place onto a baking sheet coated with cooking spray.

Cover with plastic wrap and allow the dough to rise again until almost double in size (about 25 to 30 minutes).

Cut an "X" or a few decorative slashes into the top of the raised dough if desired.

Bake at 350°F for 40 minutes or until golden brown.

Remove from pan and allow the bread to cool before slicing.