If you use frozen dark cherries - you need to defrost them. Mine was already sweetened, so I didn't add any sugar. But if you bought the fresh ones, you need to sprinkle them with 1 cup of cane sugar, let stand for 1 hour and drain the juice. Probably you would also like to make a berry compote in advance. In a small sauce pan mix all the ingredients and bring to a boil over medium-high heat, stirring often until the sugar dissolves. Let berries boil 1-2 minutes and remove from the heat. Set aside to cool. Then you'll need to make a dough. Lightly beat the eggs with a salt and milk. In a large bowl mix flour, egg mixture and water, add more water if needed. Stir with a wooden spoon (you can make the dough in a stand mixer, or with your hands). When it becomes hard to stir,  pour sticky dough on a flour surface and continue to knead until it becomes smooth and elastic. Divide the dough into 3-4 parts. Roll each part 1/4 inch thin. Using a 2.5 inch diameter glass cut as much rounds as you can. Fill each round with 3-4 cherries, pull the sides together and seal them with your fingers to form a semicircle. You can decorate your vareniki (dumplings), just press the fork's tines on the edges of vareniki. Place them on a lightly floured board and cover with a kitchen towel. You can also freeze remaining dumplings and store in freezer in ziploc bag for later use. In a large pan bring the water to a boil, add pinch of salt. Add vareniki (not all at one time) and stir with a wooden or plastic spoon to prevent from sticking to the bottom of the pan. Cook over the medium heat until they come to the surface, cook for extra 2-3 minutes and take out into a medium bowl. Add 1 tbsp of butter (left the rest butter for another portion of dumplings) and gently mix. Serve immediately with a berry compote or sour cream. Don't forget to sprinkle with a confectioners sugar!