01 - Preheat oven to 400°F. Line a baking tray with parchment paper.
02 - Heat olive oil in a skillet over medium heat. Add spring onions and garlic; sauté for 1–2 minutes until fragrant.
03 - Add spinach and cook until wilted if using fresh or heated through if using frozen. Remove from heat and let cool for a few minutes.
04 - In a bowl, combine crumbled feta, cream cheese, cooked spinach mixture, nutmeg, salt, and pepper. Mix well.
05 - Unroll puff pastry sheet on a lightly floured surface. Spread spinach and feta mixture evenly over pastry, leaving a 1/2-inch border along one long edge.
06 - Starting from the opposite long edge, tightly roll up pastry like a jelly roll. Brush border with beaten egg to seal.
07 - Slice roll into 16 equal pieces. Arrange pinwheels cut-side up on prepared tray, spacing slightly apart.
08 - Brush tops with beaten egg and sprinkle with sesame or nigella seeds if desired.
09 - Bake for 18–20 minutes or until puffed and golden brown.
10 - Let cool slightly before serving warm or at room temperature.