Ingredients:

  Amount  Measure       Ingredient -- Preparation Method
--------  ------------  --------------------------------
                        ***DOUGH***
   4      cups          all-purpose flour
   2                    eggs
     1/2  cup           sour cream
   1      teaspoon      salt
     2/3  cup           warm water
                        ***POTATO FILLING***
   3      medium        potatoes -- cooked, drained and
                        -- mashed
     1/2  medium        onion
     1/4  cup           butter
                        salt and pepper -- to taste
                        ***CHEESE FILLING***
   1      pound         dry cottage cheese
   2                    eggs -- beaten
     1/2  teaspoon      salt
     1/4  cup           butter
                        sauce
   1      large         onion -- chopped
     1/2  cup           butter

Preparation:

Dough: Mix flour, eggs, sour cream, salt, and water, a little at a time. Knead dough until firm and elastic; Cover and let rest 10 minutes. Potato Filling: Prepare potatoes, set aside. Cheese Fllling: Combine ingredients and mix. Sauce: Sauté‚onion in butter until golden. Assembly: Divide dough into three parts. On a floured surface roll dough to about 1/8-inch thick; cut into 3-inch rounds. Place a small spoonful of the filling in the center of each round, fold and press the edges together firmly to seal. Drop the pierogi in simmering chicken bouillon with 1 teaspoon of oil. Do not crowd. Simmer for 15 minutes, stirring gently to prevent sticking. Remove with a slotted spoon and drain well. Place the drained pierogi in a casserole and pour sauce mixture over all. Garnish with mushrooms.