Pour 1/2 cup of the sugar on work surface or large cutting board. Unfold 1 puff pastry sheet on sugared board. With tapered rolling pin and pressing firmly, roll pastry to 11-inch square, pressing sugar into pastry.
In food processor, place remaining 1/2 cup sugar and the orange peel. Cover; pulse, using quick off-and-on motions, until orange peel is well blended into sugar.
Sprinkle 1/4 cup orange sugar over puff pastry sheet. Beginning at 1 long side, tightly roll up dough to center of square. Repeat to roll up other side so 2 rolls are touching and rolled tightly to meet in middle; quickly roll in sugar on work surface. Wrap tightly in plastic wrap; refrigerate. Repeat process with remaining puff pastry, sugar (on work surface) and orange sugar. Refrigerate 30 minutes.
Heat oven to 425°F. Line cookie sheets with cooking parchment paper. Cut chilled rolls crosswise into 1/2-inch slices. On cookie sheets, place slices about 2 inches apart.
Bake 15 minutes, turning with spatula after 11 or 12 minutes, or until deep golden brown and sugar is caramelized. Remove from cookie sheets to cooling racks; cool completely.
In 2-cup microwavable measuring cup, microwave chocolate uncovered on High 30 to 60 seconds until chocolate is melted and can be stirred smooth. Dip half of each palmier in melted chocolate, or drizzle chocolate over palmiers with fork, allowing excess to drip off. Let stand until chocolate is set. (Refrigerate 30 minutes for chocolate to set up faster.)