Vanilla Custard Slice Recipe - The Cooking Collective (2024)

4.86 from 49 votes

Course: Dessert, Snack

Cuisine: Australian

Prep Time: 15 minutes minutes

Cook Time: 15 minutes minutes

Total Time: 30 minutes minutes

Author: Andrea Geddes

• ▢ 2 sheets frozen butter puff pastry thawed
• ▢ 1 ½ cups caster sugar 315 grams
• ▢ 1 cup custard powder 135 grams
• ▢ 4 cups thickened cream
• ▢ 1 cup milk
• ▢ 2 teaspoons vanilla bean paste or vanilla extract

For the icing

• ▢ 2 cups icing sugar
• ▢ 2 teaspoons butter softened at room temperature
• ▢ 1 – 2 teaspoons vanilla bean paste or vanilla extract
• ▢ milk or water

• Pre-heat the oven to 190 °C (374F) and place the sheets of thawed puff pastry on a flat oven tray lined with baking paper.

• Using a fork, prick the puff pastry all over to prevent it puffing up too high while baking.

• Bake for around 10-15 minutes, or until the pastry has become puffed and flaky and lightly golden.

• Place the puff pastry on a wire rack to cool.

For the custard filling

• While the pastry is baking, place the sugar and custard powder into a large saucepan and whisk together.

• Add the cream, milk and vanilla and whisk until smooth and combined.

• Over very low heat, continue to whisk the custard mixture until it becomes very thick (this may take around 10-15 minutes).

• Pour the hot custard into a bowl and place a layer of plastic or silicone wrap directly onto the surface of the custard. Refrigerate for 1-2 hours, until mostly set.

For the icing

• When you are ready to assemble the slice, make the icing. Place the icing sugar, softened butter and vanilla in a bowl and add enough milk (1 tablespoon at a time) until the mixture forms a thick but spreadable icing. Add a little more milk or water if required, until you reach the desired consistency.

To assemble

• Place one layer of puff pastry into a lined 25 x 25cm square tin or onto a flat board or plate.

• Spoon the custard over the pastry and use a spatula to spread it to the edges.

• Add the second layer of pastry over the top of the custard and top with the vanilla icing, using a flat knife or spatula to spread evenly.

• Cover the tin and refrigerate overnight (minimum 4-6 hours, but overnight is best) before cutting. If using a plate or board, place the slice into an airtight container before refrigerating.

• To cut the slice, use a clean pair of scissors or a serrated knife to cut the top layer of pastry, before running a sharp knife through the remaining layers. Serve cold, straight from the fridge.

1. Puff pastry – use ready-rolled sheets of puff pastry from the frozen section in the supermarket, for convenience. In Australia, they come in squares of 25cm x 25cm. For buttery, flaky and crispy pastry, I recommend butter puff pastry (I use Pampas butter puff pastry) over regular puff pastry, although either will work. I don’t recommend low-fat puff pastry. The pastry needs to be thawed before pricking with a fork, or the pastry may snap. Leave it on the bench at room temperature while you prepare the other ingredients.
2. Custard powder – is a cornflour-based powder which is mixed with milk or cream and heated to make an instant custard. Custard powder is commonly found in Australia, New Zealand, the UK and South Africa. I use Foster Clarks custard powder which can be found in supermarkets, but any custard powder will work. Be sure to measure the custard powder accurately to ensure it thickens properly.
3. Thickened cream – thickened cream is a whipping cream containing thickening agents that has a minimum fat content of 35%. Heavy cream or whipping cream can be used instead, but you may need to add a little cornflour to the custard mixture to ensure it thickens enough to hold its shape in the slice.
4. Milk – use whole milk or regular milk for the custard filling.
5. Vanilla bean paste – the key ingredient. I recommend using the best quality vanilla bean paste you can, as it will make all the difference in the flavour of the slice. In place of vanilla bean paste, you could use vanilla extract or real vanilla beans. I don’t recommend using synthetic vanilla essence.
6. Cook the custard over very low heat and whisk continually to ensure that it doesn’t catch on the bottom of the pan and burn. It is easy to get impatient and turn up the heat to speed up the thickening process. But whisking continually over low heat will result in a smooth custard with no lumps or burnt bits.
7. Whisk the custard until it is very thick so that it holds its shape in the slice. It may take 10+ minutes for the custard to thicken completely.
8. Cover the custard with plastic wrap, directly on the surface of the custard as it cools. This prevents a skin forming on the top of the custard as it sets. Place the cling wrap onto the bowl of custard and use your hands to gently smooth the wrap over the top of the custard.
9. Make the slice the day or night before it is required. It needs to be in the fridge overnight to finish setting.
10. For ease of assembly, you can line a 25 x 25cm x 3cm square tin with baking paper and assemble in the tin. Using a tin keeps everything together while the slice sets.
11. When baking the puff pastry, make sure the oven is fully pre-heated and the rack is in the middle of the oven. For best baking results, use an oven thermometer.
12. Storage; custard slice squares are best eaten the day after being made, but can be stored in an airtight container in the fridge for up to 3 days.
13. To slice; before slicing vanilla slice, make sure the slice is fully set and work slowly. Gently cut through the top layer of pastry with clean scissors or a serrated knife. Then use a sharp knife to slice in one go.
14. The icing will soften at room temperature, so the slice is best when served cold, straight from the fridge.
15. For passion fruit custard slice, replace the vanilla and milk in the icing mixture for fresh passion fruit pulp. Add enough to reach a thick but spreadable consistency and only add milk if needed to thin the icing.
16. The nutrition information is based on the recipe being made into 16 slices, with one slice being one serve. The nutritional information is an estimate only and does not take into account any additional toppings or sides served with the slice.
17. This recipe is made using Australian cups and spoon (metric) measurements. Due to cup sizes varying from country to country, I advise adjusting if necessary.