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