
This is one of my husband’s family recipes that I have recently discovered. The original name of this recipe was ‘Dad’s Sponge’, and the ‘Dad’ is Theo, my husband’s grandfather. The recipe was written by Joan, one of Theo’s daughters. I couldn’t resist to make this sponge that Theo loved.
The recipe requires 1 cup Custard Powder. I baked the first cake using 1 cup Custard Powder, and that created overpowering artificial vanilla smell and strikingly yellow colour. I decided to reduce the amount to 1/2 cup and add 1/2 cup Corn Starch, as Custard Powder is mostly Corn Starch.
This cake expands amazingly. I used 21cm round tin and it was almost too small. Please see the photo below. If you want to bake 1 cake, use a larger cake tin and reduce Sugar, so that the cake won’t get brown too soon. I recommend to use two 20-22cm cake tins.
Cake Tin
2 x 20-22cm Round Cake Tins *OR 22cm (OR larger) Round Cake Tin
Ingredients
4 Egg Whites *room temperature
3/4 cup Caster Sugar *reduce to 1/2 cup if you bake 1 large cake, and also if you prefer less sweet cake
4 Egg Yolks *room temperature
1/2 cup Custard Powder
1/2 cup Corn Starch Flour
1 teaspoon Cream of Tartar
1/2 teaspoon Bi-Carb Soda
Method
- Preheat oven to 170℃. Grease OR line the base and sides of two 20-22cm round cake tins, OR a 22cm (OR larger) round cake tin with baking paper.
- In a bowl, blend Custard Powder, Corn Starch Flour, Cream of Tartar and Bi-Carb Soda.
- Using an electric mixer, whisk Egg Whites in a large mixing bowl until soft peaks form. Add Sugar gradually and whisk well. Then add Egg Yolks and whisk until well combined.
- Gradually sift Dry Ingredient mixture over the Egg mixture while folding in with a large spoon or spatula, and mix until well combined.
- Pour the mixture into 2 tins (OR 1 large tin) and gently drop on the bench a few times to remove bubbles in the mixture. Bake for 20 minutes or until cakes spring back when gently touched.
- *Note: If you bake 1 large cake, it takes about 30 minutes. If you don’t reduce the amount of Sugar, the cake would get very dark brown.
- Turn out on a wire rack. Carefully peel away baking paper if you lined the tins, then leave to cool.
- *Note: I sandwiched whipped Cream and Strawberries with two cakes for the above photo. I used 23cm deep pie dish with 20cm base.
- *Note: The photo below is the same cake that is baked in a 21cm cake tin and the tin was almost too small. It would be safe to use a larger size tin.


Comments
Anonymous
25/09/2026
Hi there
Is temperature fan forced ?
Hiroko
27/09/2026
Hello. There was no such a thing like fan forced oven when Theo was cooking this cake. I am using a fan-forced oven now, and I bake most cakes at this temperature, and it works fine. If 170℃ it too high for your oven, that means the cake gets browned too quickly, lower it. Sometimes, depending on the location of the heat element, you need to change the temperature setting and cooking time. I hope you will find the best setting for your oven.
Anonymous
10/07/2026
This or something similar used to be on the nurses custard powder box. I use to make sixty odd yrs ago. Always loved it
Hiroko
11/07/2026
Thank you for your comment. Now I know that Thoe learned the recipe from the package of the custard powder. It’s been nearly 30 years since he passed. Theo was a good man, and that’s what everyone says.
Jay
23/10/2025
Hi this looks Amazing, I’m a coeliac so any cake not using flour is a treasure. When I look online for conversion of cup to grams I get different answers e.g. can I check with you about these measurements –
1 cup caster sugar = 240g (3/4 cup 180g),
Custard Powder 1 cup = 120g (1/2 cup 60g)
Cornstarch 1 cup = 120g (1/2 cup 60g),
teaspoon cream of tartar 3g or 6g?
teaspoon bi carb 5g or 7g?
Do you sift the custard powder or cornstarch?
Do you spoon it into a measuring cup or use cup to scoop (custard powder/ cornstarch)
I’d REALLY appreciate any guidance
Hiroko
24/10/2025
Hello Jay. You don’t need to weigh ingredients. 1 cup is 250ml. I often use 1/4 cup to measure 3/4 cup (3 x 1/4 cup), but 1/2 cup for 1/2 cup. You need to blend dry ingredients and sift it into the mixture as described in the method.