Prepare the dough.  Mix together:

2 cups flour
1/2 tsp. salt
1 egg (beaten)
2/3 cup milk
Tbsp. melted margarine

Mix well with a spoon.  Knead on a floured surface until smooth and elastic.  Cover and leave in a warm place for 2 hours.  Make the filling:

2 cups mashed potatoes
2 Tbsp. finely chopped chives
1/2 tsp. onion powder
1/2 cup grated medium cheddar cheese

Let filling cool.  I usually make it the day before and then refrigerate it. 

Next, the perogies must be assembled.  Roll the dough out very thin (it is somewhat spongy but will suddenly roll out nicely).  We use a plastic "Perogy Maker" that must be floured, then have a layer of dough put on top, then a spoonful of filling for each pocket, then another layer of dough, then press down and roll over with a rolling pin.  Hold the maker upside down and knock the perogies out.

Then the perogies must be cooked.  We drop them into a pot of boiling water and remove them with a slotted spoon when they come to the top.  Then we dip each perogy into a bowl of melted margarine, put them on a cookie sheet, and bake them at 400 ºF for 20-30 minutes.  The dip that we usually serve with them can be easily mixed:

1 cup yogurt
1/2 cup salad dressing
1 pkg. Uncle Dan's Southern Style mix

We usually have this as a side to some meat and vegetables.  I have a few extra perogy makers, if you would like one, let me know.