For Dough: Mix together flour, salt, pepper,(opt) garlic granules, (opt), onion granules, (opt). Add a beaten egg, yogurt or sour cream and softened butter pieces. Mix dough by hand or machine and knead for about 5 min. or till no longer sticky, add more flour if necessary. Wrap in plastic and refrigerate while you prepare your filling.
Peel potatoes. Cut in half and boil till fork tender. Cook bacon till crispy. Grate cheeses. Saute onions in butter or olive oil till tender.
Press potatoes through a potato ricer or mill. Add crumbled bacon, sauteed onions, salt, pepper, and garlic granules. Mix together well, then add cheeses and mix again.
(You can roll your dough out like you would to make ravioli, or roll all of it out at once and cut circles out and fill them, then top with another piece of dough and seal. I use the ravioli method, and my pasta roller attachment for my KA mixer). Cut dough into fourths and roll out into a long rectangle sheet about 6-8" wide, one piece at a time to about 1/8" thickness. Using a Tablespoon, put a heaping spoonful of filling about 2 inches apart on the dough. Wet edges and in between filling with a little water. Fold dough over and seal is filling pocket. Cut between mounds and seal. Make sure to get all air out of pockets.
Place on a baking sheet lined with parchment paper. Do not over lap, they will stick together. Repeat until all dough is used. I got 18 out of mine. Any leftover potato mixture can be eaten right out of the bowl!!!
Place a few pierogies at a time in salted boiling water. Boil for about 5-6 min. Dough will become a whiter as the cook and start to float. Then drain and place in a skillet with some butter and/or olive oil and fry to firm up dough a little and add color.
Serve with your favorite marinara sauce or dipping sauce.