Preheat your oven to 375°F (190°C).

Sauté the chopped onion in a skillet with olive oil over medium heat until translucent, about 5 minutes.

Add the fresh spinach to the skillet and cook until wilted, about 2-3 minutes, then remove from heat.

Whisk together the eggs, crumbled feta cheese, garlic powder, salt, and pepper in a mixing bowl. Fold in the sautéed spinach and onion mixture.

Roll out the thawed puff pastry on a floured surface and cut into desired shapes.

Spoon the spinach-feta filling onto each pastry piece and seal the edges.

Bake on a parchment-lined baking sheet for 25-30 minutes until golden brown.