Ingredients
1 1/2 cups sugar
1 cup unbleached all-purpose flour
3/4 teaspoon baking soda
1/4 teaspoon kosher salt
1/3 cup buttermilk
1/2 cup safflower oil
2 tablespoons golden rum, such as Bacardi Gold
1 large egg plus 1 large yolk
1 teaspoon pure vanilla extract
1 ripe banana, mashed until smooth (1/3 cup)
2 large or 3 small ripe mangoes (2 pounds, 6 ounces total), peeled, 2 sides cut off each, and each side sliced into 5 pieces
Preparation
Preheat oven to 350 degrees. Heat 1/2 cup sugar and 2 tablespoons water in a small saucepan over high, stirring, until sugar is dissolved, about 3 minutes. Let boil, without stirring, until dark amber, swirling pan to color evenly and washing down sides with a wet pastry brush to prevent crystals from forming. Immediately pour into a 9-inch round cake pan; swirl to evenly coat bottom of pan.
Whisk together flour, baking soda, salt, and remaining 1 cup sugar in a medium bowl. In another bowl, whisk together buttermilk, oil, rum, egg and yolk, vanilla, and banana. Whisk buttermilk mixture into flour mixture until smooth and combined.
Arrange mangoes in pan on top of caramel, in a tightly packed single layer. Pour batter into pan.
Bake until a tester inserted in center of cake comes out clean, 45 to 50 minutes. Let cool in pan on a wire rack 15 minutes. Run a knife around edge of pan, invert cake onto a plate, and let cool completely before serving.
