Place puff pastry sheet on work surface. Cut in half, forming two (2) 9 1/2- by 4 3/4-inch rectangles.
Arrange half of the prosciutto slices on one (1) puff pastry rectangle, leaving 1/2-inch border along one side. Sprinkle the prosciutto with 1/2 of the fresh basil or sage, then top with 1/2 of grated Gruyere cheese.
Brush plain border with the beaten egg. Starting at the long side opposite border, roll up pastry jelly-roll style, pressing gently to seal log. Wrap in plastic paper.
Repeat with remaining puff pastry rectangle, prosciutto, basil or sage, Gruyere cheese, and egg to form second log.
Refrigerate pastry logs, seam sides down, until firm, at least 3 hours and up to 2 days.
When ready to serve, position rack in center of oven and preheat to 400F. Line two large baking sheets with parchment paper.
Cut logs crosswise into 1/2-inch-thick rounds. Arrange rounds on prepared sheets, spacing 1-inch apart.
Bake, one baking sheet at a time, until pastries are golden brown, approximately 16 minutes. Remove from oven using a metal spatula, transfer pastries to racks, and cool slightly. Serve warm.
Makes approximately 30 pinwheels.
* I used the Pepperidge Farm ones from the freezer section.
Prosciutto and Gruyere Pinwheels Recipe: https://whatscookingamerica.net/Appetizers/ProsciuttoPinwheels.htm