01 -
Preheat the oven to 365°F (185°C) and line a baking sheet with parchment paper.
02 -
Heat olive oil in a large skillet over medium-high heat. Add diced onion and sauté until translucent, about 3–4 minutes.
03 -
Incorporate chopped mushrooms and cook, stirring often, until all liquid has evaporated and mushrooms are tender, approximately 8–10 minutes.
04 -
Reduce heat to low. Stir in mayonnaise, salt, pepper, minced garlic, and grated Parmesan. Cook for 1 minute, then transfer mixture to a bowl and cool slightly.
05 -
Roll out each puff pastry sheet on a lightly floured surface to approximately 12 × 16 inches.
06 -
Spread the cooled mushroom mixture evenly over the surface of each pastry sheet. Sprinkle shredded mozzarella over the filling.
07 -
Starting from a long edge, firmly roll up each pastry sheet into a tight log.
08 -
Using a sharp knife, slice each log into 1-inch thick rounds and arrange them flat on the prepared baking sheet.
09 -
Brush the tops of the pinwheels with the beaten egg to create a golden crust.
10 -
Bake on the center rack for 30–40 minutes, or until the pastry is golden brown and the centers are set.
11 -
Remove from oven and allow to cool for several minutes before serving warm.