In a medium mixing bowl, combine softened cream cheese, grated Parmesan, mayonnaise, garlic powder, onion powder, and freshly ground black pepper. Mix until smooth and creamy, about 2-3 minutes.

Thaw and thoroughly drain the frozen spinach, then chop finely. Fold it into the creamy mixture until evenly distributed.

On a lightly floured surface, unroll chilled puff pastry. Spread the creamy spinach filling evenly, leaving a 1-inch border.

Starting from one edge, roll the puff pastry tightly into a log shape. Wrap in plastic wrap and refrigerate for about 30 minutes.

Preheat your oven to 400°F (204°C) and line a baking sheet with parchment paper.

Slice the chilled log into ½-inch rounds, placing them on the prepared baking sheet with space in between. Brush with egg wash.

Bake for 15-20 minutes, or until puffed and golden brown. Cool slightly before transferring to a serving platter.