In a mixing bowl, combine the softened cream cheese, grated Parmesan, mayonnaise, garlic powder, onion powder, pepper, and thoroughly drained spinach. Mix until smooth and well blended.

On a floured surface, roll out the thawed puff pastry. Spread the prepared filling evenly across the pastry, leaving a border on one long edge. Carefully roll the pastry tightly from the opposite edge and seal the seams well.

Wrap the filled log in plastic wrap and refrigerate for at least 30 minutes. For quicker chilling, freeze for about 15 minutes.

Preheat your oven to 400°F (200°C).

Remove the chilled log from the fridge, slice it into half-inch pieces, and place them on a baking sheet lined with parchment paper. Brush the tops lightly with the beaten egg. Bake for 15-20 minutes or until puffed and golden brown.

Allow the pinwheels to cool slightly before serving warm.