Chocolate School Cake with Mint Custard

When I made a chocolate school cake with chocolate custard a few weeks ago, I had a few people tell me that their school had green custard instead.

GREEN CUSTARD ???? I like green, I also like mint, so I wanted to try it.

Turns out mint custard and chocolate cake is a great combo, I loved the way this tasted.

A square slice of the chocolate school cake on a white plate with mint custard being poured on top

Video Tutorial

Chocolate School Cake with Custard

If you’re not from the UK, or if you’re like me and have forgotten everything about your childhood, you might not know what chocolate school cake. 

A lot of primary schools in the UK would give this cake as a desserts.

It was just a slice of plain chocolate cake, with custard on top. Some schools had regular custard, some had a pink custard and some had a green custard.

Whenever I hear people talk about this dessert, they say they love it but then they also talk about how dry it was.

I promise this recipe will not give you a dry cake, we’re recreating the school cake but making it better!

A slice of the chocolate school cake after the mint custard had been poured onto it

Ingredients for the chocolate cake

The cake for this dessert is pretty easy to make.

All we’re doing is mixing the wet ingredients, mixing the dry ingredients, and then putting them together. 

Here’s the ingredients that are needed for the cake!

  • Cocoa powder – I like to mix this with the wet ingredients. Hydrating the cocoa powder gives it a better chocolaty taste.
  • Coffee – adding some coffee also gives a better chocoalty taste.
  • Oil – any flavourless oil works, I like to use vegetable. I use oil instead of butter in this recipe, it makes the cake more moist.
  • Plain Yoghurt – this also makes the cake more moist.
  • Eggs
  • Self-raising flour – I like to use self raising instead of plain. The only reason is because it’s easier, I don’t have to add any raising agents. 
  • Sugar – We’re using a mixture of brown and granulated sugar. The brown sugar gives the cake a great flavour.
The baked square chocolate cake on top of a sheet of baking paper

Common Questions

Do I have to add coffee?

In the recipe, you will see that I add 100ml of hot water that has been mixed with 1 teaspoon of coffee.

Coffee in chocolate cake helps bring out the chocolate flavour.

I feel like chocolate cake always tastes so much better with a little coffee in it.

It doesn’t make the cake taste like coffee at all, if you’re worried about that. 

But you could leave it out if you wanted too, just make sure to still add in the 100ml of hot water.

Substitutes for the yoghurt?

I love adding yoghurt to my chocolate cakes, it makes them so much more moist.

I like to use full fat plain yoghurt.

If you don’t have it….I recommend buying it.

But if you don’t want too, sour cream is the best substitute. Or buttermilk will work well too.

The last resort is to just use regular milk instead. The cake will be a little less moist if you replace the yoghurt with milk, but it will still be good!

Can I use a different flour?

If you’re from the US,  you might not be able to get self-raising flour very easily. 

You can use the same amount of plain/all purpose flour instead. Just add 2 teaspoons of baking powder to it.

The chocolate cake inside of an 8 inch square cake tin after being baked

Making the mint custard

Making the custard is also easy. All you need to do is add the ingredients into a pot and heat until the mixture has thickened. 

Here are just a few tips!

Keep the heat on medium

The custard has egg yolks in, so you want to keep the heat on medium throughout the whole cooking process.

The reason for this is because we don’t want the eggs to get too hot, if they do, the can end up scrambling.

So then you will have pieces of scrambled eggs in your custard. We don’t want this.

Keep stirring 

You want to keep stirring during the cooking process. Try not to walk away from it.

Again, this is because we don’t want the eggs to get too hot.

But with that being said, if your eggs do scramble a little, it’s not a huge deal. We’re sieving the mixture anyway.

Sieve the custard

The last step in making the custards is to sieve is.

This is to get out any eggs that might have scrambled but also any other lumps that could have formed because of the corn flour! 

The baked square chocolate cake with a slice being taken out of it

The mint flavour

So to give the custard a mint flavour, I used peppermint extract.

I did try using actual fresh mint leave at first. But in order to get enough mint flavour in the custard, I had to use A LOT of mint leaves.

So I decided it’s just way easier to use peppermint extract instead.

In the recipe I wrote that you need 1-2 teaspoons of the extract. The amount if totally up to you though.

If you want a milder mint taste, add less, if you want a stronger mint taste, add more!

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Chocolate School Cake with Mint Custard

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  • For the cake:
  • 50g cocoa powder

  • 100ml hot water mixed with 1 teaspoon instant coffee

  • 100ml any flavourless oil (I used vegetable)

  • 100g plain yoghurt

  • 3 eggs

  • 175g self-raising flour

  • 125g granulated sugar

  • 125g brown sugar

  • For the mint custard:
  • 6 egg yolks

  • 80g granulated sugar

  • 1/4 teaspoon salt

  • 20g corn flour

  • 480g whole milk

  • 30g unsalted butter

  • 1-2 teaspoon peppermint extract

  • Plus some food colouring


  • Making the cake:
  • Start by pre-heating your oven to 170c/325f, also grease and line an 8 inch square cake tin.
  • In a bowl or jug, mix together the cocoa powder, the hot water/coffee, and the oil. Then mix in the yoghurt and eggs.
  • In a separate large bowl, whisk together the flour and both sugars. Add the wet mixture into this bowl and whisk just until you get a smooth batter.
  • Pour this into your prepared cake tin and bake for around 45-55 minutes, or until a toothpick inserted into the centre comes out clean.
  • Making the mint custard:
  • Whiles your cake is baking, you can make the custard.
  • In a pot, add the egg yolks, sugar, salt, corn flour and milk. Mix this, then place this pot over medium-low heat.
  • You want to keep heating this mixture, whiles constantly stirring, until it thickens. Try not to increase the heat, if the egg yolks get too hot, they will scramble.
  • Once the mixture has thickened, take it off the heat and add in the butter. Mix until this has melted.
  • Now add in the peppermint extract and food colouring. You can adjust the amount of peppermint extract, add it to taste.
  • Push this custard through a sieve to get out any lumps.
  • Cover with cling film until you're ready to use it. Make sure that the cling film is touching the top of the custard, so that a skin doesn't form.
  • Serving:
  • Once the cake has baked and cooled down for a bit you can cut into it and serve.
  • Just take the cake out of the tin, cut it, pour some warm custard on top and then enjoy!