If you’ve ever stepped into a Vietnamese bakery or scrolled through Vietnamese food pages, chances are you’ve seen the glistening, golden-topped cupcakes called “bánh bông lan trứng muối” (Sponge cupcake with salted egg yolk). These little sponge cupcake with salted egg yolk, pork floss and a luscious egg yolk sauce, are a beloved fusion of savory and sweet, soft and rich, traditional and modern.

This treat is especially popular in the South of Vietnam, especially in Vung Tau and Saigon. But you don’t have to wait until you are there in Vung Tau or Saigon to enjoy them – these cupcakes are surprisingly easy to make at home. The recipe below makes 12 mini sponge cupcakes, each topped with a rich swirl of egg yolk sauce sauce, pork floss and a salted egg yolk that brings an irresistible umami punch.

Let’s dive in.

Why Sponge Cupcake with Salted Egg Yolk and Pork Floss?

Vietnamese cuisine is known for balancing contrasting flavors, and bánh bông lan trứng muối is a perfect example. The airy sponge, the creamy sauce, and the salted egg create a dynamic trio that’s both comforting and exciting.

As we all know, sponge cake is a light, airy cake made from eggs, flour, and a bit of butter and milk for richness. It is one of the most common cakes in the world, with many, many variations. When it comes to Vietnam, it seems that a bakery in Vung Tau—a coastal city in the south of the country—created a new variation using some very Asian ingredients: salted egg yolks and pork floss. These toppings make this version of sponge cupcake so special: savory salted egg yolks are baked to a golden hue, paired with shredded pork floss (ruốc or chà bông), and drizzled with a silky, mayo-like egg yolk sauce. The combination is addictive—like biting into a cloud of buttery sweetness with a burst of salt and richness from the yolk. And yes I and my friends are all into it that we always buy some everytime we have a chance for an afternoon tea!

These cupcakes are perfect for gifting, sharing at potlucks, or just treating yourself on a quiet afternoon with a cup of tea. Once you’ve had your first bite, don’t be surprised if they become a regular in your baking rotation (like me :D)

Ingredients Breakdown

Before we start baking a bunch of sponge cupcake with salted egg yolk, let’s take a closer look at what you’ll need:

Sponge Cupcakes (12 cakes)

3 Eggs
45g All-purpose flour (about 6 tbsp)
45g Cornstarch (about 5 tbsp)
36g Butter (2.5 tbsp)
45g Unsweetened milk (3 tbsp)
45g White sugar (3.5 tbsp)
3g Vanilla extract (about 3/4 tsp)
6g Lemon juice (for stabilizing the egg whites) (1 tsp)

Sweet Egg Yolk Sauce

2 Egg yolks
20g White sugar (1.5 tbsp)
2g Salt (1/3 tsp)
10g Lemon juice (2 tsp)
300g Neutral vegetable oil (like canola or sunflower oil) (1 1/3 cups)

Salted Egg Yolks & Pork Floss

6 to 12 salted egg yolks (depending on if you want 1 or 2 per cupcake)
100g pork floss (about 3.5 oz)

You can buy pre-made salted eggs at most Asian grocery stores. If you’re feeling ambitious, you can also cure your own some salted egg yolks (here’s my guide to do it).

Step-by-Step: How to Make Sponge Cupcake with Salted Egg Yolk

Step 1. Prepare the Salted Egg Yolks

If your yolks are from store-bought salted eggs, rinse them gently to remove excess whites. Steam them for 8–10 minutes or bake them at 160°C (320°F) for 8 minutes until slightly firm and lightly oily. Let them cool while you make the cake.

Step 2. Make the Sponge Cake Base

Preheat your oven to 160°C (320°F) and line a 12-cup muffin tin with cupcake liners.
Separate the egg yolks and whites into two bowls. In one bowl, beat the egg yolks with the milk, melted butter (cooled slightly), and vanilla.

Sift together the all-purpose flour and cornstarch, then mix into the yolk mixture until smooth.

In another bowl, beat the egg whites with lemon juice until foamy, then gradually add the sugar. Continue whipping until soft peaks form.

Fold the whipped egg whites gently into the yolk-flour batter in batches, being careful not to deflate the airiness.

Divide the batter evenly into the 12 cupcake liners and gently tap the tray to remove large air bubbles.

Bake at 160°C (320°F) for about 20–22 minutes, or until a toothpick comes out clean. Let them cool before decorating.

Step 3. Make the Sốt Dầu Trứng (Egg-Oil Sauce)

This sauce is the velvety, savory-sweet crown of the cupcake.

In a mixing bowl, add the egg yolks and sugar. Whisk until pale and slightly thickened.

Slowly drizzle in the oil while whisking continuously. It’s a lot like making mayonnaise—slow and steady wins the race. The mixture should emulsify into a glossy, thick sauce.

If it’s too runny, chill it briefly in the fridge before piping or spooning onto your cakes.

Step 4. Assemble the Cakes

Once the cakes are cool:

Spoon or pipe a generous swirl of the sốt dầu trứng on top of each cupcake.

Place one or two salted egg yolks on each cake. Then you can sprinkle pork floss (ruốc) around the salted egg yolks for extra texture and umami.

Tips for Success

Here’s some tips for you to make sure that your sponge cupcakes will be perfect:

Don’t overmix the batter, or your sponge may turn dense.
Keep ingredients at room temperature for smoother mixing.
Whip the egg whites to soft peaks, not stiff—this gives a tender, fluffy sponge.
The sweet egg sauce can be made in advance and stored in the fridge for 1–2 days.

Ready to bake? Let your kitchen smell like warm sponge cake and toasty salted eggs—and let the joy of Vietnamese flavors take over.

Sponge Cupcake with Salted Egg Yolk

These little sponge cupcake, crowned with salted egg yolks, pork floss and a luscious egg yolk sauce, are a beloved fusion of savory and sweet, soft and rich, traditional and modern.

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Course: Dessert

Cuisine: Asian, Vietnamese

Keyword: banh bong lan trung muoi, sponge cake with salted egg yolk

Cook Time: 45

Servings: people

Calories: 762kcal

Author: Anh Truong

Equipment

1 Hand Mixer

2 Mixing Bowls

1 Cupcake Baking Tray

12 Cupcake Liners