Preheat oven: to 180°C / 350°F.
Grease a medium-sized baking dish (around 25x35 cm / 10x14 in).
Prepare the filling:
In a bowl, crumble the white cheese.
Add eggs, yogurt (if using), and a few tablespoons of melted butter.
Mix well with a fork until evenly combined.
Assemble the banitsa:Lay one sheet of filo pastry in the baking dish. Brush lightly with melted butter.Add another sheet, brush again, then spoon some of the cheese mixture over it. Repeat layering: filo → butter → filling → filo → butter → filling, until all ingredients are used.Finish with a couple of buttered sheets on top.Tip: You can also roll each sheet with a bit of filling and coil them into a spiral for the traditional circular shape like I've done here in the pictures.
Brush the top layer with the remaining butter.
Place in the oven and bake for 35–40 minutes, until golden brown and crisp on top.
Let it rest for 10–15 minutes before cutting into slices.