Defrost puff pastry sheets according to package instructions.
Whisk together sugar, cinnamon, and salt.
Generously dust work surface with sugar mixture. Place one puff pastry sheet over sugar. Generously coat top of puff pastry with sugar mixture. Use a rolling pin to roll dough a to 16x10-inch rectangle.
With the longer end facing you, fold in the sides towards the middle. Coat exposed puff pastry with sugar mixture. Fold the sides towards the middle once again. Coat exposed puff pastry with sugar mixture. Fold the right side over the left side. Coat exposed puff pastry with additional sugar mixture.
Place on a parchment lined baking sheet. Repeat with folding process with second puff pastry sheet.
Cover assembled logs with plastic wrap. Freeze for 30 minutes, or up to overnight.
Remove frozen logs from freezer. Using a sharp knife, slice logs into 1/2-inch thick cookies. Place sliced cookies on parchment lined baking sheet. Cover with plastic wrap. Freeze for 1 hour until solid. NOTE: At this point, once frozen, you can store sliced cookies in an airtight container and keep frozen for up to a month. Bake as directed.
Preheat oven to 375°F. Arrange frozen palmiers on parchment lined baking sheet (or silicone mat lined sheet) about 2 inches apart. Bake for 15-18 minutes, rotating midway, until sugar has caramelized and puff pastry is golden brown. Transfer to wire racks and let cool completely in the pans. Store in an airtight container at room temperature for up to 5 days.