Step 1

Thaw the puff pastry, if frozen: If your puff has been in the freezer, place it in the refrigerator to thaw overnight. Alternatively, place it on the counter to thaw, but keep an eye on it. Once the pastry is pliable, but still cool, it's ready — about 30 minutes.

Step 2

Roll out the puff pastry: If using store-bought dough, lightly roll the dough just enough to even out the seams. If using homemade dough, roll the dough out to a rectangle that is 1/8 to 1/4 inches thick.

Step 3

Sprinkle with sugar: Sprinkle most of the sugar in an even layer over the surface of the dough. Roll over it lightly with a rolling pin to press the sugar into the dough.

Step 4

Fold the sides inward: Fold the left and the right sides of the dough inward so they meet in the middle.

Step 5

Sprinkle with more sugar: Sprinkle the remaining sugar over the dough. Again, roll over the dough lightly to press in the sugar.

Step 6

Fold the dough in half like a book: Fold the left side over the right side, like closing a book. This should make a very long, flat length of dough with the first two folds sandwiched in the middle.

Step 7

Refrigerate 30 minutes: Transfer the log to a baking sheet. Cover with plastic wrap and chill for 30 minutes to give the dough time to firm up. This will make them easier to cut and also help them puff better in the oven.

Step 8

Heat the oven to 425°F. Place a rack in the middle position.

Step 9

Slice into cookies: After chilling, transfer the log back to the work surface. Use a sharp knife to slice the log across into cookies roughly 1-inch wide.

Step 10

Transfer to baking sheet: Transfer the cookies to a parchment-lined baking sheet, laying them cut-side up. Sprinkle the cookies with more sugar, if desired. Make sure to space the palmiers a few inches apart — they will puff quite a lot in the oven! Bake in batches if necessary; place the un-baked cookies in the fridge to chill between batches.

Step 11

Bake for 18 to 20 minutes, until dark golden. If it seems like the sugar on the bottom of the cookies is starting to burn before baking is finished, transfer the baking sheet to a higher oven rack and reduce the heat to 375°F.

Step 12

Cool and eat! Let the palmiers cool for a few minutes on the baking sheet, then transfer to a cooling rack to cool completely. They will become crispier as they cool. Palmiers are best the day they are made, but can be stored in an airtight container for several days. They will gradually lose their crispiness over time.