Preparation Method
- Make the filling: In a large skillet, over medium heat, melt butter. Add mushrooms, shallot, sage and salt and stir to combine. Add wine and cook until mushrooms are very soft and most of the liquid has been absorbed, 10-15 minutes. Transfer mixture to a bowl and allow to cool. When mixture has cooled, stir in Gruyere cheese.
- Make the pinwheels: On a lightly floured surface, unfold the pastry sheet and cut in half lengthwise. Arrange one half of the sheet with long side facing you. Using a floured rolling pin, gently roll out the pastry until the rectangle has increased in size by about 50%, and is now closer in shape to a square. Lightly brush the edge farthest from you with beaten egg. Spoon half of the mushroom mixture onto the pastry sheet and spread evenly, avoiding the egg-brushed edge. Starting with the side nearest you, carefully roll the pastry into a log, like a jelly roll. Wrap the log in wax or parchment paper. Repeat with second half of pastry to form another log. Chill the logs, seam-sides down, until firm, at least 2 hours or up to 2 days.
- Bake the pinwheels: Line a baking sheet with parchment paper. Set aside. Position the oven rack in the middle position. Preheat oven to Bake 400°F. Slice the logs crosswise into 1/2-inch pinwheels. Each log should make about 18 pinwheels. Arrange pinwheels cut-sides down, about 1 inch apart on prepared baking sheet. Bake in batches, until pastry is golden brown, 14-15 minutes. Serve warm.
