Lemon Lover's Cake | America's Test Kitchen

Ingredients

• 2 cups (8 ounces/227 grams) cake flour
• 1½ cups (10½ ounces/298 grams) granulated sugar , divided
• 1 teaspoon baking powder
• ¼ teaspoon baking soda
• ¾ teaspoon salt
• ¾ cup buttermilk
• 5 large egg yolks plus 3 large egg whites
• 8 tablespoons unsalted butter , melted and cooled
• 3 tablespoons vegetable oil
• 1½ teaspoons vanilla extract
• ⅛ teaspoon cream of tartar
• 1 tablespoon grated lemon zest
• 2 cups lemon curd
• Sugared lemon slices (optional)
• 20 tablespoons (2½ sticks) unsalted butter , softened
• 2½ cups (10 ounces/283 grams) confectioners' sugar
• ⅛ teaspoon table salt
• 2 tablespoons heavy cream
• 1 tablespoon grated lemon zest plus ¼ cup juice
• 2 teaspoons vanilla extract
• 1 (4 ounces/113 grams) chunk white chocolate