espresso chiffon cake with fudge frosting

INGREDIENTS

• 1/4 cup (60 ml) neutral vegetable oil, such as soybean, canola or vegetable blend
• 6 eggs, separated
• 6 tablespoons (90 ml) freshly brewed espresso, cooled to room temperature (Huntsman recommends freshly-brewed over hydrating espresso powder, which she feels can be too bitter)
• 2 teaspoons (10 ml) vanilla extract
• 1 1/3 cups (170 grams) cake flour
• 1 1/2 cups (300 grams) sugar
• 1 teaspoon baking powder
• 1/2 teaspoon ground cinnamon
• 1/2 teaspoon salt
• 1/2 teaspoon cream of tartar
• 1/3 cup hot, freshly brewed espresso
• 1/3 cup sugar
• 1/3 cup dark rum, such as Meyer’s
• 6 ounces unsweetened chocolate, melted and cooled
• 4 1/2 cups confectioners’ sugar (no need to sift)
• 3 sticks (12 ounces) unsalted butter, at room temperature
• 6 tablespoons half-and-half or whole milk
• 1 tablespoon vanilla extract