Put the flour into a big bowl.
Cut cold butter into a small cube then place it into the flour. Using a spoon, stir the butter and flour until all the butter is well coated.
Combine salt and water then pour half of it and sugar into the mixture. Stir again for a while then pour the rest of the water.
Transfer the mixture to the work surface. Bring everything together using your hand into a rough dough. Do not knead the dough.
Flour the surface of the rough dough then roll it with a rolling pin lightly. While rolling, flatten the side, top, and bottom of the puff pastry using your hands to make a rectangle.
Fold ⅓ bottom of the puff pastry up and ⅓ top of the puff pastry down, then wrap it with plastic wrap and rest it in a fridge for at least 2 hours or overnight.
Remove the puff pastry from the fridge. Dust your work surface, and puff pastry with flour then roll the puff pastry into a rectangle with a rolling pin. Fold ⅓ bottom of the puff pastry up and ⅓ top of the puff pastry down. After folding, rotate the dough 90 degrees and roll the dough vertically lengthwise. Repeat this step at least four times.
Wrap it with plastic wrap and rest it again in a fridge for 60 minutes.
Preheat the oven to 170°C (338°F)
After resting time, place the puff pastry on a work surface. Trim each side of the puff pastry then split it into two. Slice cookies 1-1.5 cm each. Brush sides of pastry with water, then stick 3 pieces of pastry for 1 palmier.
Place them on a baking tray lined with non-stick baking paper, leaving some space in between. Sprinkle the top of the palmier with sugar. Bake for 20-23 minutes.
Heat a saucepan half filled with water over medium heat. Bring the water to a simmer.
Place about ⅔ of the dark chocolate into a heatproof mixing bowl. With the heat turned off, double boiler the chocolate until it reaches 100°F. The temperature should not exceed 115°F.
After the chocolate melted and reached 100°F, remove it from the saucepan and cool it down with the rest of the chocolate chips that have not been melted. Keep stirring until it reaches 84°F.
After the palmier are baked and cooled, coat each side of the palmier with melted chocolate, and scrape the excess chocolate. Place it again on a baking tray lined with non-stick baking paper. Chill in a refrigerator for 15 minutes or until the chocolate hardens.
The chocolate palmier carre are ready to serve. Enjoy!