Prepare the oven and pan. Preheat the oven to 400°F (200°C). Lightly grease a large rimmed baking pan.
Make the filling. Place the cottage cheese, sour cream, eggs, and salt in a large bowl. Stir until evenly combined. The filling will still have small cheese curds.
Prepare the phyllo. Unroll the phyllo dough on a clean work surface. Keep unused sheets covered with plastic wrap and a slightly damp towel to prevent them from drying out.
Fill and roll. Lay out one phyllo sheet and lightly drizzle with some of the oil. Spoon a line of filling along one edge, leaving a little space at the ends. Gently roll into a long log.
Arrange in the pan. Place the roll seam-side down in the prepared pan. Repeat with the remaining sheets, oil, and filling, distributing the filling evenly and arranging the rolls side by side.
Add the topping. Pour half the milk (100 ml) evenly over the rolls. Scatter the butter pieces over the top.
Bake. Bake for approximately 30 minutes, or until golden brown and the filling is set.
Finish with milk. Remove from the oven and brush with the remaining 100 ml of milk. Let rest for about 10 minutes, until the milk has absorbed. Cut into 8 portions and serve warm.