In a mixing bowl, combine cream cheese, Parmesan cheese, mayonnaise, garlic powder, onion powder, and black pepper. Stir until smooth and fully blended.

Squeeze dry thawed spinach and fold it into the cream mixture until evenly mixed.

Lightly flour your countertop and unroll a sheet of puff pastry. Spread the spinach dip filling evenly over the pastry, leaving one long edge clear.

Starting from the filled edge, tightly roll the pastry into a log shape and seal the edges.

Wrap the log in plastic wrap and refrigerate for at least 30 minutes to firm up.

Preheat your oven to 400°F (200°C). Slice the chilled log into half-inch rounds and arrange on a baking sheet.

Whisk an egg and brush the tops of the pinwheels with the egg wash. Bake for 15-20 minutes or until puffed and golden.

Allow to cool slightly before serving.