Best Upside Down Orange Cake with Silky Diplomat Cream

A slice of upside down orange cake with layered diplomat cream served on a red dessert plate.

Best Upside Down Orange Cake with Silky Diplomat Cream

Course: Cakes, Dessert

Cuisine: European, Transylvanian

Diet: Low Salt

Keyword: orange cake, orange cake recipe, upside down orange cake, upside down orange cake recipe

Prep Time: 2

Cook Time: 25

Cooling time: 1

Total Time: 1 2 25

Servings: servings

Calories: 299kcal

Author: Timea

A showstopping, European-style upside down orange cake layered with feather-light sponge, sweet macerated citrus slices, and a cloud of orange-vanilla diplomat cream. Make-ahead friendly and perfect for holidays, celebrations, and Sunday dinners.

Print Recipe

Metrics - US Customary

Equipment

1 springform cake pan 8 or 9-inch / 20–23 cm
1 electric mixer hand mixer
1 Dutch oven pot approx. 9–10 inches / 24–25 cm wide
3 bowl mixing bowls
1 Plastic wrap heavy-duty kitchen foil

Ingredients

For the Citrus Mosaic & Syrup:

1.5 kg orange 5-6 medium, fresh sweet oranges (mix of Navel and Blood oranges)
2 tablespoon sugar granulated

For the Sponge Cake:

6 pieces eggs large, free-range, separated
6 tablespoon sugar 75 g, granulated
6 tablespoon flour 60 g, all-purpose
1 teaspoon baking powder 5 g,

For the Citrus Diplomat Cream:

400 ml milk 1.7 cups whole milk
3 pieces egg yolks large, free-range
6 tablespoon sugar granulated, divided: 3 tablespoon for milk, 3 tablespoon for yolks
3 tablespoon corn flour 25 g, cornstarch
1 teaspoon vanilla essence or aroma
1 piece orange zest finely grated zest only
500 ml double cream 2 cups, heavy whipping cream (chilled)

Instructions

1. Macerate the Oranges:

Peel oranges completely, removing all bitter white pith. Cut into thin, even rounds (approx. 5 mm / ¼-inch). Lay in a shallow bowl, sprinkle with 2 tablespoon sugar, and rest for 1 hour. Strain and reserve the extracted citrus juice for soaking.

Bake the Sponge:

Preheat oven to 180°C (350°F / Gas Mark 4, fan assisted). Grease an 8 or 9-inch springform pan.
Beat egg yolks and 6 tablespoon sugar with an electric mixer for 2–3 minutes until pale and creamy.
Sift flour and baking powder into the yolk mixture; gently whisk until just combined.
In a separate clean bowl, whip egg whites to stiff peaks.
Gently fold one-third of the egg whites into the batter to lighten it, then fold in the remaining whites using wide, gentle sweeping motions.
Pour batter into the pan and bake for 22–25 minutes (avoid opening the oven for the first 15 minutes). Cool completely on a wire rack, then slice horizontally into 3 even layers.

Cook the Diplomat Cream:

Heat milk, vanilla, and 3 tablespoon sugar in a saucepan over medium heat until steaming.
In a bowl, whisk egg yolks, remaining 3 tablespoon sugar, and cornstarch until smooth.
Slowly pour ½ cup of warm milk into the yolks while whisking constantly, then pour everything back into the saucepan.
Cook over medium-low heat, whisking constantly, until thick and bubbling (1–2 minutes).
Stir in the grated orange zest. Remove from heat and cool completely to room temperature.
Whip chilled double cream to stiff peaks. Gently fold the cooled custard into the whipped cream until smooth and airy.

Assemble & Chill:

Line a deep round pot (or Dutch oven) completely with plastic wrap or kitchen foil, leaving overhang on all sides.
Arrange macerated orange slices neatly along the bottom and lower sides of the pot.
Spread one-third of the diplomat cream over the oranges, filling all gaps.
Place the first sponge layer on top; drizzle with 2–3 tablespoons of reserved orange juice.
Repeat layering: diplomat cream, remaining orange pieces, second sponge layer, orange juice, remaining cream, and finish with the final sponge layer.
Fold overhanging foil over the base. Refrigerate for 24 hours to set.

Unmold & Serve:

Unwrap the top foil. Place a serving platter upside down over the pot, securely invert the cake, lift off the pot, and peel away the foil to reveal the citrus mosaic. Slice with a warm knife and serve chilled.

Video

Notes

- Completely remove white pith to eliminate bitterness.
- Ensure the custard base is fully cooled to room temperature before folding with whipped cream to prevent melting.
- For extra holiday flavor, stir 1 tablespoon orange liqueur (Cointreau or Grand Marnier) into the soaking syrup.

Nutrition