Preheat your oven to 375°F (190°C) and line a baking sheet with parchment paper.

In a medium skillet, heat 1 tablespoon of olive oil over medium heat. Add 1 finely chopped onion and 2 minced garlic cloves; cook for about 5 minutes until the onion softens.

Toss in 4 cups of fresh spinach and stir for 2-3 minutes until wilted.

Transfer the mixture to a mixing bowl, add 1 cup of crumbled feta cheese, 4 ounces of cream cheese, and season with salt and pepper. Mix well.

Roll out 1 sheet of thawed puff pastry to about 1/8 inch thick and cut into 3x3 inch squares.

Place about 1 tablespoon of the filling in the center of each square. Fold the corners over to create a triangle shape.

Press the edges to seal and crimp with a fork for decoration if desired.

Brush the top of each roll with a beaten egg and bake on the prepared baking sheet for 20-25 minutes until golden.

Let the rolls cool for about 10 minutes before serving warm.