Step 1

Make sure your puff pastry is thawed before you start -cold, but thawed. (Note if it is too warm, it may fall apart, if too cold, it will be too stiff to roll.)

Step 2

Preheat oven to 400F

Step 3

Heat oil in an extra-large skillet or dutch oven, over medium-high heat. Add mushrooms, onions, garlic, salt and rosemary and saute, stirring often, until mushrooms release all their liquid. Turn heat down to medium, and continue sauteing until all the liquid has evaporated, be patient, this will take a little time! Once the mushrooms are relatively dry in the pan, splash with the sherry wine and balsamic vinegar and again, sauté on medium heat until all the liquid has cooked off. This is important- you absolutely do not want a watery filling ( it will turn into a mess!).  Add the toasted chopped pecans, pepper, truffle oil. Taste, adjust salt to your liking. At this point, you could fold in some cheese if you like.

Step 4

15-20 minutes (you could make the filling a day ahead and refrigerate).

Step 5

Carefully unroll the puff pastry onto a parchment-lined baking sheet (if it seems stiff, let it thaw a few more minutes until pliable).  Place half the filling in a mound along the center (see photo) and working quickly, roll the pastry up, and over, seam side down. Fill and roll the second sheet.

Step 6

.

Step 7

using a razor blade or sharp knife with your choice of design – cross-hatch, herringbone, leafy vine or just simple diagonal slits.

Step 8

Place the sheet pan on the middle rack in the oven for 35 minutes, checking at 2o mins, and rotating pan for even browning if necessary. Let the pastry bake until it is a really deep golden color – to ensure it’s done and flaky all the way through. You may need to add 5 more minutes depending on your oven. Convection will help if you have this setting (use it for the last 5-10 minutes) Please, let’s not have any pale pastries!!! Nice and golden!

Step 9

for  5-10 minutes before cutting and serving. Garnish with Rosemary Sprigs. It’s OK to serve at room temp, but warm is best.

Step 10

See notes for making ahead!