Strawberry-Elderflower Cake

Preheat oven to 350 °F. Butter a 9"-diameter cake pan and sprinkle with granulated sugar. Whisk flour and salt in a small bowl; set aside. Whisk eggs and 1 cup granulated sugar in a heatproof bowl and place over a saucepan of simmering water (bowl should not touch water). Heat, whisking constantly, until sugar is dissolved and mixture is warm to the touch, about 4 minutes. Remove bowl from heat and, using an electric mixer on high speed, beat egg mixture until it is pale and tripled in volume, about 5 minutes. Gently fold reserved dry ingredients into egg mixture in 3 additions, then fold in melted butter. Scrape batter into prepared pan and smooth top. Bake cake until golden brown and a tester inserted into the center comes out clean, 25 –30 minutes. Transfer pan to a wire rack and let cake cool in pan before turning out.