Healthier Magic Lemon Custard Cake

9 Squares
1 hr 20 min

Have you heard of the Magic Custard Cake? It is a cake consisting of 3 layers, a pie crust like fudgey bottom, custard middle and moist sponge cake top layer. However this is made all with the one batter which separated into the respected layers while it bakes. It’s magic! or science :)

I have been so curious about this cake since I saw it making the rounds in social media over the past month or so. But i’m not a big fan of vanilla cakes, so i decided to make a lemon version.

The most popular recipe is by Jo cooks, this is her version. My recipe is adapted from this version.

As usual, I also wanted to make it lighter and less sweet, so I substituted half the sugar with monk fruit sweetener (my fav sugar replacer but you can use stevia or just sugar, just don’t replace it with any liquid sweetener), use skim milk and replace almost half of the flour with wholemeal spelt flour to get a bit of wholegrain goodness in (I find wholemeal spelt flour more pleasant tasting than wholemeal flour)

When I was mixing the batter, I was actually very skeptical about this cake working, the batter is very thin, it calls for 500 ml of milk! it also bakes for a much longer time than my usual cakes.

But lo and behold, it came out really great. There are definitely 3 distinct layers. The bottom layer is almost like a pie crust, it’s dense and fudgy. The middle layer is a soft custard. The top layer reminds me of the sponge in a tiramisu, like a super moist, soaked in milk sponge. My cake seems to have a really tall cake layer and thinner custard layer, not sure if it’s because I’m using less sugar and includes some wholegrain flour, but I’m not complaining. The top layer is my favourite :)

I hope you will try this easy recipe, it really is a very fascinating dessert. Please tag me at @dessertsforlunch on IG :)

the 3 layers :)

Healthier Magic Lemon Custard Cake

Recipe details

  • 9  Squares
  • Prep time: 20 Minutes Cook time: 1 Hours Total time: 1 hr 20 min
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Egg yolk mixture

  • 4 egg yolks at room temperature
  • 10 g or 1 tbsp sugar
  • 40 g or 3 tbsp monk fruit sweetener or stevia
  • 1 tsp vanilla extract
  • 125 g or 1/2 cup olive oil spread or unsalted butter
  • 60 g or 1/2 cup plain flour
  • 55 g or 1/2 cup wholemeal spelt flour
  • 485 ml or 2 cups lukewarm skim milk
  • 15 ml or 1 tbsp lemon juice
  • 1 tsp lemon zest (optional)

Egg white mixture

  • 4 egg whites at room temperature
  • 50 g or 1/4 cup sugar
  • 1 tsp white vinegar


Preheat oven to 160C or 325F
Butter and line 8" x 8" / 20cm x 20cm square cake tin.
Beat egg whites with 50 g or 1/4 cup sugar and vinegar until stiff peaks form. Set aside.
Place the eggs and sugar/sweetener in a bowl and beat with a mixer until it turns paler yellow - about 1 minute.
Add vanilla extract and olive oil spread and beat until well incorporated - about 30 seconds to 1 minute.
Add flours and mix until just combined.
Add lemon juice and zest to the lukewarm milk.
Pour the milk/lemon mixture. Gradually and beat until well combined.
Use a spatula or wooden spoon to fold in egg whites into the batter, one third at a time, just until incorporated. Be gentle, we don’t want to knock the air out of the egg whites. Don’t worry if you have lumps of egg whites in the batter. The batter will be very liquidy.
Pour the batter into the prepared cake tin.
Bake until the top is golden brown and the cake does not ‘jiggle’ if you gently shake the tin. About 40-60 minutes.
If the top is already golden brown but still jiggles, cover the top with foil and return to the oven to bake fo another 10 minutes or until done.
Cool in the tin, then turn out carefully onto a cooling rack, and turn out again onto a plate.
Cool completely before cutting into squares.


  • Fold the egg whites gently. Don't worry if there are lumps.

Sunny Blevins
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  • EmmaSurf EmmaSurf on Sep 18, 2020

    I understand that it is different with less decadent ingredients but I missed the thicker custard. FYI your comment on tre leches called, it has 3 creams but doesn't really divide into the distinct layers like your cake. I love any lemon so I appreciate your tweaking the vanilla recipe.

    • Sunny Blevins Sunny Blevins on Sep 19, 2020

      Thanks for your comment, I’ve actually been thinking about this too, I will give this another go soon to see if I can have a thicker custard while remaining healthyish

  • Cel Cel on Sep 19, 2020

    Any grain free flour I can use instead of spelt? Almond, walnut, sunflower, coconut, lupin? Anything other than wheat?

    • See 1 previous
    • Marilyn Marilyn on Sep 20, 2020

      Hi. As to Cel's question, I too am looking for an alternative that is a grain free flour, ie almond, coconut, etc. Your alternative suggestion has 2 rice ingredients and maize, all are grains. I love the look and idea of this cake, we are tho eating grain free for brain health. Thanks!