01 - Preheat the oven to 400°F. Line a baking tray with parchment paper.
02 - In a bowl, combine the spinach, feta cheese, cream cheese, garlic, half the beaten egg, dill, black pepper, and salt (if using). Mix well until evenly blended.
03 - Unroll the puff pastry sheet on a lightly floured surface. Spread the spinach and feta filling evenly over the pastry, leaving a ½ inch border along one long edge.
04 - Starting from the opposite long edge, tightly roll up the pastry into a log, sealing the edge with a little water.
05 - Using a sharp knife, slice the log into ¾ inch thick pinwheels (about 20 pieces). Place them flat, cut side up, on the prepared baking tray.
06 - Brush the tops of the pinwheels with the remaining beaten egg.
07 - Bake for 18–20 minutes or until puffed and golden brown.
08 - Let cool slightly before serving warm or at room temperature.