Citrus Medley Upside-Down Cake

1. Preheat and Prepare Pan

Preheat your oven to 350°F (175°C) and position the oven rack in the middle. Prepare a 9-inch round cake pan by lining the bottom with parchment paper. This ensures even baking and easy removal later.

2. Prepare Oranges

Grate 2 teaspoons of zest from one of the oranges and set it aside. Peel the oranges, trim the ends, and slice them crosswise into ¼-inch thick rounds, removing any seeds you encounter. This step is crucial as it determines the presentation and flavor of your cake.

3. Prepare Caramel Base

Pour 4 tablespoons of melted butter into the bottom of your prepared pan and swirl it to coat the surface evenly. This forms the base for the caramelized topping.

4. Create Sugar Mixture

In a small bowl, whisk together ½ cup of sugar, 1 teaspoon of cornstarch, and ⅛ teaspoon of salt. Sprinkle this mixture evenly over the melted butter in the pan. Arrange the orange slices in a single layer over the sugar mixture, nestling them snugly together and pressing them flat so they lie evenly.

5. Mix Dry Ingredients

In a large bowl, whisk together 1 cup of all-purpose flour, 1 teaspoon of baking powder, and the remaining ½ teaspoon of salt. This will be your dry ingredient mixture.

6. Mix Wet Ingredients

In a second large bowl, whisk together ½ cup of sour cream, 2 large eggs, 1 teaspoon of vanilla extract, the reserved orange zest, and the remaining 1 cup of sugar. Whisk until the mixture is smooth and well combined, which should take about a minute.

7. Combine Wet and Dry Ingredients

Gradually whisk the remaining 6 tablespoons of melted butter into the sour cream mixture until it is fully incorporated. Add the flour mixture and whisk until just combined. The batter should be smooth but not overmixed.

8. Pour and Bake

Pour the batter over the arranged orange slices in the pan and smooth the top with a rubber spatula. Bake the cake in your preheated oven for 50 to 55 minutes, or until the top is deep golden brown and a toothpick inserted into the center comes out clean. This baking time ensures the cake is fully cooked and the top is nicely caramelized.

9. Cool and Invert

Allow the cake to cool in the pan on a wire rack for 20 minutes. Run a knife around the edge of the pan to loosen the cake, then carefully invert it onto a serving platter. Discard the parchment paper and let the cake cool for at least 1 hour before serving.

10. Finish with Marmalade

To finish, microwave 2 tablespoons of orange marmalade in a small bowl until it becomes fluid, about 20 seconds. Using a pastry brush, gently brush the marmalade over the top of the cake to give it a beautiful, glossy finish. Now, your Citrus Medley Upside-Down Cake is ready to serve. Enjoy!