01 - Combine flour, instant yeast, sugar, and salt in a large bowl. Add warm milk and olive oil. Knead for 5 to 7 minutes until a soft, elastic dough forms. Cover and let rise in a warm place for 45 minutes or until doubled in size.
02 - Preheat oven to 375°F (190°C). Line a baking sheet with parchment paper.
03 - Mix spinach, mozzarella, feta, parsley, garlic, and black pepper in a medium bowl until well combined.
04 - On a lightly floured surface, roll the dough into a 10 by 14-inch rectangle, spreading the filling evenly over the surface, leaving a 1/2-inch border.
05 - Roll the dough tightly from the long side to form a log. Pinch the seam to seal, then slice into 12 equal pieces.
06 - Place the rolls cut side up on the prepared baking sheet. Brush the tops with beaten egg and sprinkle sesame seeds if desired.
07 - Bake rolls for 20 to 25 minutes until golden brown. Allow to cool slightly before serving.