Mix the flour and salt in a large bowl. Add the butter and milk and mix lightly until the flour is absorbed. (Add a little warm water as needed.) Knead until the dough sticks together, cover and allow to rest for a few minutes, then knead until smooth. Cover and set aside. Place the dough in a lightly oiled bowl, turn, and cover for about 1/2 . Place 1/4 of the dough on a floured work surface, re-covering the rest of the dough. Roll into a circle, starting at the center and rolling outwards to maintain an even thickness, turn over and from the center, roll the dough out to about 1/8-inch thickness. Run a hand under the bottom to loosen it. With a cut into rounds with diameter around 3 inches. When done cutting, place 1 spoon of the filling on one side of each, flipping the other half over the top and sealing with your fingers. Be sure to seal these well. Place each of the varenyky on a floured cooky sheet and cover them with a towel. Repeat with the remaining dough, saving the scraps until last. Use as little flour as possible in this process or the scraps will be come tough and heavy. While you are doing the last ones, place a saucepan with water on the stove, to make the water boil. Gently drop 12 to 15 varenyky into of boiling water. Do not overcrowd. Stir and cook for about 3 - 4 minutes. Drain in a collander and place on a lightly oiled cookies sheet, shaking to coat with a thin film to prevent sticking.