Method:

Filling:

Peel and quarter potatoes, cover with water, and cook until soft. Meanwhile, cook chopped onions in melted butter until golden. Drain and rice potatoes. Shred cheddar cheese or crumble bryndzia. Add onions, cheese, salt, and pepper to potatoes and mix well. Allow to cool, stirring occasionally. Filling may be refrigerated for several days. Do not freeze filling. Note: leftovers may be used to make breakfast cakes or as filling for potato boats or stuffed green peppers. 

Dough:

Combine flour and salt in a large bowl, forming a well in the middle. Add butter and milk and mix lightly until flour is absorbed. (Add a little warm water if needed.) Knead until dough sticks together, cover and allow to rest for a few minutes, then knead until smooth. Cover and set aside. (The dough should be somewhat soft, since more flour is added as dough is rolled out.) Or, in processor, combine flour, salt, and butter and stir a few times. With machine running, add liq, uids until a ball forms. Allow to rest a few minutes, then process until smooth. Place dough in a lightly oiled bowl, tum, and cover for about 30 minutes before rolling out. (It may be wrapped in plastic and refrigerated for a day or so, brought to room temperature, and then rolled out.)