Beat eggs, then add flour and salt, mixing well. Add cottage cheese and sour cream and beat again. Heat oven to 325 degrees.
Place 2 sheets of filo dough in a well buttered 13x9 inch rectangular baking dish. Brush 2 tablespoons butter over dough. Spread about 6 tablespoons cheese mixture over dough. Repeat with 2 layers of dough and 6 tablespoons of cheese mixture. Brush each layer of dough with butter. Continue layering in these quantities until only 2 sheets of dough remain and all cheese is used up.
Add last 2 sheets of dough and drizzle any remaining butter over it. Bake until top is golden, about 1 hour. Cake will rise, but once removed from oven will sink to normal height.
To serve, cut in squares. Serve warm as a side dish to meat or brunch dish. Serves 12.
