A Summery Cake with Lemongrass Syrup

Name: A Summery Cake with Lemongrass Syrup
Cuisine: French
Ingredients: 3 stalks of fresh lemongrass, cut into chunks; ½ tsp baking powder; 1½ cups (175 g) self-rising flour; ¾ cup (175 g) unsalted butter, at room temperature; ½ cup plus 2 tbsp (125 g) superfine sugar; grated zest of 1 lemon; 3 large eggs; Pinch of salt; 1 cup (200 g) sugar