In a small bowl, dissolve the yeast and sugar in warm water. Let it sit for about 5 minutes until frothy.
In a large bowl, combine the flour and salt. Make a well in the center and pour in the yeast mixture and olive oil.
Mix until a dough forms. Knead on a floured surface for about 5-7 minutes until smooth and elastic.
Place the dough in a lightly oiled bowl, cover with a cloth, and let it rise in a warm place for about 1 hour, or until doubled in size.
In a medium bowl, mix together the feta cheese, cottage cheese, chopped parsley, egg, and black pepper until well combined.
Preheat your oven to 375째F (190째C).
Punch down the risen dough and divide it into 2 equal portions.
On a floured surface, roll out each portion into a rectangle.
Spread the cheese filling evenly over one of the rectangles of dough. Place the second rectangle on top to form a sandwich.
Pinch the edges to seal and transfer to a baking sheet lined with parchment paper.
Brush the top of the dough with the beaten egg and sprinkle with sesame seeds if desired.
Bake in the preheated oven for 25-30 minutes, or until golden brown and cooked through.
Allow to cool slightly before slicing. Serve warm or at room temperature.
Enjoy your meal!