Madeleines, miniature French sponge cakes, are made in special scallop-shell-shaped pans. These are enhanced with rose water and sprinkled with pale-pink sugar.
In a medium bowl, sift together the flour, baking powder, and salt.
In electric mixer, beat eggs and 1/2 cup granulated sugar on medium until light, 3 to 4 minutes. Beat in vanilla. Fold in flour mixture. Fold in butter. Cover with plastic; chill for 30 minutes.
Meanwhile, heat oven to 425 degrees; place rack in center. Spray two scallop-shell pans with cooking spray. Use spoon to fill molds three-quarters full. Bake 5 minutes. Reduce heat to 400 degrees. Bake 5 to 8 minutes more, until lightly golden. Immediately tap out madeleines onto a cooling rack. (Let madeleines cool scallop side up to avoid any creases or lines from rack.) Repeat with remaining batter. Let cool.
Make rose-water syrup by combining remaining 1/2 cup granulated sugar with 1/2 cup water in a small saucepan. Bring to a boil, stirring to dissolve sugar; reduce to a simmer, and cook over low heat 2 to 3 minutes to combine. Set aside to cool. When cool, stir in rose water. Set aside.
Place sanding sugar in a small bowl. Use a toothpick to add small amounts of powdered food color to sanding sugar, stirring until you get desired shade of pink.
Use a small paint brush to sugar edges of madeleines one at a time; dip brush into rose-water syrup, and paint rim of each madeleine. Sprinkle sanding sugar over damp edges. Repeat on remaining madeleines. Madeleines are best served within 1 to 2 days of baking. Store in airtight container at room temperature.