Preparation

• Heat oil in a skillet over medium heat. Add garlic and cook until fragrant, 1 to 2 minutes. Stir in spinach and cook until warmed through, 3 to 5 minutes; season with salt and mix well. Transfer to a bowl; mix in feta cheese until combined.
• Preheat the oven to 400 degrees F (200 degrees C). Grease 2 baking sheets.
• Lay 1 sheet of puff pastry on a lightly floured surface and cut in half lengthwise. Roll 1 half out with a rolling pin so it is wide enough to fold twice lengthwise. Mix egg and milk together in a small bowl.
• Spread ⅙ of the spinach mixture lengthwise in the center of puff pastry. Roll one side over the filling and brush other side with egg mixture. Roll over again to seal.
• Brush top of roll with egg mixture and sprinkle with sesame seeds. Cut roll into 6 equal-sized rolls. Repeat with the remaining puff pastry. Place cut rolls onto the prepared baking sheets.
• Bake in the preheated oven until spinach rolls are puffed up and golden, 20 to 25 minutes.