Preheat the oven to 350°F. Grease a 13x9-inch baking dish. Put the potatoes into a saucepan, cover them with water, and bring to a boil. Reduce the heat and simmer until the potatoes are fork-tender. Drain, then add ¼ cup of the butter and the half-and-half and whip. Set the potatoes aside. In a small skillet over medium heat, melt ½ cup of the butter, add the onion, and cook until translucent. Add the sauerkraut, heat thoroughly, then set aside. In a medium bowl, mix the farmer’s cheese with the eggs, then set aside. In small saucepan over medium heat, melt the remaining butter. Layer a sheet of phyllo dough in the prepared baking dish and generously brush it with the melted butter. Repeat. Layer one-quarter of the mashed potatoes, one-quarter of the cheese mixture, and one-quarter of the sauerkraut. Distribute one-quarter of the kielbasa slices on the sauerkraut. Repeat the double phyllo layers, butter, and filling layers three more times. Cover with six to eight phyllo layers, buttering between each. Bake for 30 minutes, or until golden brown. Cut into squares.