Step 1 Heat the oven to 225 degrees. Line a baking sheet with parchment paper.
Step 2 Beat the egg whites to a stiff froth, 2 minutes,then very slowly add the sugar and rosewater, beating hard until soft peaks form with a glossy sheen, 3 to 5 minutes. Fill a piping bag fitted with a large star tip with the sugar mixture and carefully pipe 1 1/2-inch circles on the baking sheet, spacing them 1 inch apart.
Step 3Bake until lightly browned, 35 minutes, then turn the oven off and let the cakes sit for 45 minutes. Remove the baking sheet from the oven and carefully remove the cakes from the parchment paper.