Step 1In a bowl, combine the sugar and six rose geranium leaves. Rub the leaves and sugar between your fingertips to release the oils, rubbing the leaves until they are very soft and fall apart. Transfer the sugar mixture to a strainer and sift the sugar into a medium bowl and set aside. Reserve the muddled leaves.
Step 2In a heavy saucepan, combine the remaining leaves with the 5 ounces butter. Add the reserved leaves to the pan. Over medium heat, melt the butter with the leaves until the butter bubbles in the center and leaves turn soft and brownish, stirring frequently, about 4 minutes. Remove from heat and set aside to cool until the mixture is just warm. Strain the butter into a small bowl, pressing on the leaves to extract as much butter as possible. Discard the leaves.
Step 3Heat the oven to 375 degrees. Butter and flour a madeleine pan. Whisk the eggs and salt into the sugar in the bowl until just well blended. Stir in the flour, then gradually whisk in the melted butter. Spoon the batter by rounded tablespoonfuls into the prepared mold.
Step 4Bake the madeleines until browned at the edges and puffed and set in the center, about 14 minutes. Cool the madeleines in the pans for 5 minutes, before carefully removing. Repeat until all of the madeleines are baked.