The recipe is from Confections of a Foodie Bride.
1 sheet puff pastry, thawed
1/2-3/4 cup pesto
Preheat oven to 375º. Roll out the puff pastry on a piece of parchment into a 12x12 inch square. Spread the pesto within a 1/2 inch of each side of the pastry. Using your spatula, make three indentions on the top edge of the dough at 3 inches, 6 inches, and 9 inches to divide the sheet into quarters.
Fold the left and right edges of the puff pastry halfway to the center of the dough (to the closest quarter-mark indention). Fold the sides to the middle again until they're almost touching. Fold the two halves together like a book.
(You can stop here and freeze for later use. Just let the logs thaw a bit and then proceed)
Cut into 1/2 inch slices and place onto parchment-lined baking sheets. Whisk egg and water together and brush over the palmiers. Bake for 8 minutes, flip, and bake for an additional 6-8 minutes. Palmiers are best the day of baking.