Prepare the filling by mixing cream cheese, grated Parmesan, mayonnaise, garlic powder, onion powder, black pepper, and drained spinach in a bowl until smooth.
Roll out the puff pastry and spread the filling evenly while leaving one edge clear. Roll tightly into a log.
Chill the rolled log for 30 minutes in the refrigerator before slicing into rounds.
Preheat the oven to 400°F (200°C). Place sliced pinwheels on a baking sheet lined with parchment paper and brush with an egg wash.
Bake for 15–20 minutes until golden brown and puffed.