Preheat the oven to 375 degrees Fahrenheit, and lightly grease a round 12 inch baking pan with butter.
To prepare the filling, add the feta, ricotta, parmesan and eggs to a medium bowl. Season with the black pepper, nutmeg, and salt to taste. Mix well.
Combine the melted butter and olive oil in a small bowl. Lay one sheet of phyllo lengthwise on a work surface, and lightly brush with the butter mixture. Place a second sheet directly on top and brush lightly again.
Spoon a narrow line of cheese filling along the edge of the pastry leaving about 1 inch at each end. Roll loosely into a long log, enclosing the filling. Rolling too tightly will prevent the filling from expanding during baking. Repeat with the remaining phyllo and cheese filling.
Create a small spiral in the centre of the baking tin with the first log of pastry. Then place each new log around the previous one to create a continuous spiral. Continue until the pan is filled.
Brush the entire spiral generously with the remaining butter mixture, and sprinkle over the sesame seeds. Bake for 45-55 minutes, until deeply golden brown and crisp. Rest for 10-15 minutes before slicing.