Let's cook.
Preheat your oven to 400°F (200°C). Line a baking sheet with parchment paper.
On a lightly floured surface, carefully unroll the thawed puff pastry sheet.
In a small bowl, combine the crumbled feta cheese, chopped Kalamata olives, fresh oregano, and black pepper. Mix well.
Spread the feta and olive mixture evenly over the entire surface of the puff pastry, leaving a small border on one long edge.
Starting from the long edge opposite the border, tightly roll the puff pastry into a log. Brush the small border with a little beaten egg to seal the seam.
Using a sharp knife, slice the log into 12 equal pinwheels, each about 1/2 inch thick.
Place the pinwheels cut-side up on the prepared baking sheet, leaving some space between them. Brush the tops of the pinwheels with the remaining beaten egg.
Bake for 18-20 minutes, or until the pastry is golden brown and puffed.
Let cool for a few minutes on the baking sheet before serving warm or at room temperature.
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