Vanilla Custard Cake

slice of vanilla cake with custard filling.

Soft and fluffy vanilla cake sandwiched with custard buttercream and creme patissier

Prep Time40

Cook Time35

Total Time1 15

Servings: slices

Ingredients

For the Vanilla Pastry Cream

3 cups Whole Milk 710g / 720ml
1 tablespoon Vanilla Extract
7 Egg Yolks
¾ cup Granulated Sugar 150g
6 tablespoon Cornstarch
1 ½ sticks Unsalted Butter 170g

For the Vanilla Cake

1.25 cup Whole Milk 300g / 300ml
⅓ cup Vegetable Oil 66g / 80ml
3 Large Eggs
2 ¾ cups Cake Flour 312g
1 ¾ cups Granulated Sugar 350g
1 tablespoon Baking Powder
½ teaspoon Salt
1 teaspoon Vanilla Extract
2 sticks Unsalted Butter 227g

For the Custard Buttercream

Vanilla Pastry Cream (⅔ of the pastry cream prepared for the filling)
4 sticks Unsalted Butter 454g
⅓ cup Powdered Sugar 38g
1 teaspoon Vanilla Extract
¼ teaspoon Salt

Cups - Grams

Instructions

Make the Pastry Cream (Custard)

Make the pastry cream 2 - 24 hours ahead of time, as it needs time to cool and thicken. Use the steps below or see my Vanilla Pastry Cream post for more detailed instructions and process pictures.
Put the egg yolks in a bowl with the sugar and cornstarch- whisk to combine until pale and thick.
Put the milk and vanilla in a saucepan over medium heat until it is scalding hot. This means you can see steam rising from it and tiny bubbles appearing on the surface. Don't let it boil.
Drizzle a small amount of hot milk into the egg yolk mixture and whisk, then add a little more, and repeat until everything is together in the bowl. It's important to do this slowly and gradually so you don't scramble the eggs
Pour the whole mixture back into the saucepan.
Return to the heat, whisking constantly until it begins to boil.
Boil for 1-2 minutes or until you see thick bubbles bursting on the surface. It should be thick enough that you can draw a line in it on the back of a spoon - if it isn't, keep boiling until you reach that stage. Remove from the heat.
If done gradually, there shouldn't be any lumps in the custard, but if there are, you can pass it through a fine mesh sieve to remove them.
Whisk in the butter one small piece at a time, making sure it melts into the mixture completely before adding the next piece
Cover with plastic wrap (make sure the plastic wrap is touching the surface of the pastry cream to prevent a skin from forming) and 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

Preheat oven to 350°F/180°C (160°C for fan-assisted) and grease two 8-inch cake pans. Ensure the butter, eggs, and milk are at room temperature before beginning.
Split the milk into two containers, one with ½ cup of milk (118g) and one with ¾ cup of milk (177g).
Mix the ½ cup of milk with the vegetable oil and set aside.
Mix the remaining milk with the eggs and vanilla. Whisk together lightly and set aside.
Place the flour, sugar, baking powder and salt into the bowl of your mixer and turn on low with your paddle attachment
Slowly add the butter, one small chunk at a time. Once it's all in, it should look kind of like chunky breadcrumbs
Add the milk/oil mixture and slowly turn your mixer up to a medium speed. Beat for exactly two minutes
Scrape the sides of your bowl to make sure there are no lumps, then turn the mixer back on low.
Add the milk/egg mixture slowly and mix on low until just combined.
Divide into cake pans and bake for 30-40 minutes - check to see if a toothpick comes out clean before removing from the oven.
Let the cakes cool in the pan for at least 30 minutes before removing them.

Make the Custard Buttercream

About an hour before you start, move roughly ⅓ of the pastry cream into a separate bowl, cover with plastic wrap 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.
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)
Add the room temperature pastry cream one tablespoon at a time until it is all added, whipping in between additions.
Add the vanilla and salt and mix in.
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.
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 (see notes for how to fix it).

Assemble the Cake

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
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.
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
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.

Notes

Pastry Cream

The vanilla pastry cream will be used for both the custard buttercream and as a filling. Make one batch of it and then divide it as per the instructions above.
It's best to make the pastry cream in advance so it has time to cool for at least 2 hours, but you can also make it the day before.

*If your buttercream curdles - 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!