Dissolve the sugar in the lukewarm water, sprinkle the yeast over it and let stand 10 minutes. Combine the remaining ingredients add to the yeast mixture. Add enough flour to make a soft dough. Knead on a floured board or counter top until smooth and satiny. Place in a bowl cover and let rise until double, punch down knead a few times and let rise again. (About 1hr-11/2hr. total).
Meanwhile peel,dice and boil potatoes until done, mash with potato masher, add salt and pepper and Cheez Whiz if using. Allow to cool.
Roll dough out to about 1/4 inch thickness and cut into 11/2 or 2 inch squares or circles.
Place about 1/2 tsp of potato mixture in the center of the dough fold over, sealing the edges well.
Place on cookie trays and bake in pre-heated 350 deg oven for about 15 minutes or until golden brown.
For the sauce, saute the butter over medium heat until bubbly, add onions, salt and pepper. When onions are translucent, turn heat down to medium low and add whipping cream.
Bring to a boil and simmer 5 minutes more.
Place baked perishkes in heat proof or oven proof container.
When sauce is done, pour over perishkes, stir, let sit for 5 minutes and enjoy.
Note: When they have cooled they can be placed in zip lock bags without the sauce-they freeze well.
When you want to re-heat them, place in Corning Ware or similar dish, microwave for about 3-5 minutes and pour freshly made sauce over them, stir and serve.