Custard Cake

This Custard Cake consists of ridiculously fluffy vanilla sponge cake layered with custard buttercream and a homemade custard filling.

I tested and re-worked so many iterations of this vanilla custard cake until every element was PERFECT. I switched to a reverse creaming method to make the sponge extra light and fluffy, and changed the frosting recipe to make it even more custardy.

I'm convinced there is something magical about this cake. I brought Chris a slice of it to try... and the next morning - boom! An engagement ring.
Clearly, it was the cake.

Ingredients

Because this custard cake has multiple components, timing and temperatures matter more than usual. Taking the time to read the recipe fully before you start will make all the difference here.

• Milk - For best results, use full-fat milk. Whole milk is the foundation of the custard, and if you don't use a full-fat milk, you will not get that gorgeous, thick, creamy texture. And you really can't have a custard cake with mediocre custard!
  
• Butter - The quality of the butter is important in this recipe; try to use something with a high fat percentage.
  
• Sugar - Granulated sugar (caster sugar in the UK) is best.
  
• Eggs - You will need egg yolks for the custard and whole eggs for the vanilla sponge. Save your leftover egg whites for another recipe, like my Strawberry Angel Food Cake.
  
• Vanilla - Of course, vanilla is an important ingredient as the cake, buttercream, and custard filling all revolve around it! Try to use a high-quality vanilla extract or vanilla bean paste, or if you like you can even use whole vanilla pods. The quality of the vanilla you use will really shine through in this recipe.
  
• Corn Starch - The cornstarch (cornflour in the UK) helps to thicken the pastry cream.
  
• Flour - This vanilla sponge works best with cake flour, but you can also use all-purpose flour (plain flour).
  
• Vegetable Oil - This helps to keep the cake moist; you can substitute with any neutral oil.
  
• Powdered Sugar - (Icing sugar) This is optional to sweeten the custard buttercream; you can leave it out or add less of it if you prefer a less sweet frosting.

It is crucial that your 'cold ingredients' (i.e. butter, milk, eggs) are brought to room temperature before starting this bake. There are a number of components that could curdle or go wrong easily, so make it easier on yourself and keep everything at the same temperature!

See the recipe card for the full recipe.

Equipment

• Saucepan
• Whisk
• Stand Mixer
• Sieve
• 8-inch Cake Pans
• Cake Leveler (optional, but helpful)

How To Make Custard Cake

There are three components to this custard cake: the vanilla cake, the custard filling (pastry cream), and the custard buttercream. We use the same pastry cream both as a filling and to create the frosting, so you only have to make it once.

Make the Custard Filling

The first step for making this cake is to make the pastry cream - also known as crème pâtissière or custard. You can make the custard a day or two in advance if you want to break the recipe into easier steps. This is the same filling used inside Boston Cream Pie, so you know it's good!

1. Whisk the egg yolks, sugar, and cornstarch together in a large bowl until pale and thick.
2. Heat the milk and vanilla in a medium saucepan and slowly warm over medium heat until scalding. This means that steam is rising from the milk, and tiny bubbles will start to appear on the surface. Don't let it boil.

3. Once the milk is scalding, drizzle a small amount of warm milk into the egg yolk mixture and whisk, then add a little more, repeat until everything is together in the bowl, then pour the whole mixture back into the saucepan.
   
   It's important to add the milk to the eggs slowly to temper the eggs and prevent them from scrambling.

4. Keep heating the custard on medium heat, whisking constantly until it begins to boil with thick bubbles bursting on the surface. Boil for 1-2 minutes. Remove from the heat. It should be thick enough that you can draw a line in it on the back of a spoon.

5. If the custard has been cooked gradually, there shouldn't be any lumps in the custard, but if there are, you can pass the pastry cream through a sieve into a bowl to remove them.
6. To enrich the pastry cream, whisk in the butter one small piece at a time, making sure it melts into the mixture completely before adding the next piece.

7. Cover with plastic wrap (make sure the plastic wrap is touching the surface of the pastry cream to prevent skin from forming). Let it cool down a little and then refrigerate for at least two hours. I like to make this the day before and let it sit overnight, but it can be used after 2 hours.

Make the Vanilla Cake

This is my go-to Vanilla Cake recipe - I use it as a base for lots of other cakes and cupcakes. If you want to make an even lighter version, try my Genoise Sponge.

Prepare Ingredients

Preheat oven to 350°F / 180°C (or 160°C for a fan-assisted oven) and grease two 8-inch cake pans.

Split the milk into two containers, one with ½ cup of milk (120ml) and one with ¾ cup of milk (180ml).

Mix the ½ cup of milk with the vegetable oil and set aside. Mix the ¾ cup of milk with the eggs and vanilla. Whisk together lightly and set aside.

Sift Dry Ingredients

Sift the flour, sugar, baking powder, and salt into the bowl of your mixer and turn on low with your paddle attachment.

Add Butter

Slowly add the butter, one small chunk at a time, letting it mix for a few seconds in between additions. Once it's all in, it should look kind of like chunky breadcrumbs.

Make the Custard Buttercream

This Custard buttercream, or 'German Buttercream' is silky smooth and full of rich, creamy vanilla flavor.

1. Before you start, move roughly ⅓ of the pastry cream into a separate bowl and place it back in the fridge. Put the remaining ⅔ of the pastry cream in a covered bowl on the counter to come to room temperature. At the same time, remove your butter from the fridge so it can also come to room temperature.
2. Once it's at room temperature, you can start making the frosting. Place all the butter in your stand mixer and beat with a whisk attachment on high speed until pale and fluffy (about 3-5 minutes)
3. Add the pastry cream one tablespoon at a time until it is all added, whipping in between additions.
4. Add the vanilla and salt and mix in.
5. At this stage, taste-test the buttercream to see how much sweetness you would like to add. Add the powdered sugar a little at a time, whipping after every addition, until the desired sweetness is reached.
6. The custard buttercream should be lovely and silky smooth - if it curdles it's usually just a sign that the ingredients were not the same temperature - to fix it just take the bowl and very gently heat the bottom of it over a bain marie and whisk until it comes together again (it shouldn't take long), then return to the stand mixer and it should be beautifully silky again!

Assemble the Custard Cake

1. Once completely cooled, cut each of the cakes in half so you should have four thin cake layers. I use this cake leveler, but you can also use a serrated knife.
2. Start building your layers, first with cake, then a layer of custard buttercream, smoothing it out as you go. Add your second layer of cake on top and put on a slightly thinner layer of custard buttercream.
3. On top of the thinner layer of custard buttercream, pipe a border of buttercream around the outside of the middle layer, and fill the middle with half of the cold custard you reserved in the fridge. Add the next layer of cake on top
4. Add another generous layer of buttercream, followed by your final cake layer. Decorate the cake however you like - smooth, naked, semi-naked, or messy. Pipe some rosettes around the top of the cake and then pour the remaining custard on top of the cake, in the middle of the rosettes.

Storage

Store your assembled custard cake in an airtight container in the refrigerator for up to 4 days.

All the elements can be made ahead of time:

• You can make the vanilla cake 3 days ahead and store it in an airtight container at room temperature.
• The pastry cream can be made 2 days ahead, covered with plastic wrap, and stored in the fridge.
• The custard buttercream can also be stored in the fridge for 2 days in an airtight container.

More Custard Dessert Recipes

If you are a custard lover, you may enjoy some of these custard recipes!

Watch How To Make Custard Cake (Video)

Watch my full step-by-step tutorial video on how to master this custard cake.

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