This vegan vanilla slice (or custard slice) is just like the classic bakery treat but with NO dairy or eggs! It has a thick layer of creamy custard between two layers of puff pastry, and is topped with an optional icing.
Ingredients you'll need
Notes about the ingredients
Vegan-friendly custard powder. A few mainstream custard powders are accidentally vegan and don't contain milk or egg powder! I used Foster Clarks custard powder (available from major supermarkets) which is partially sweetened. Other vegan-friendly brands include Bird's and the Woolworths brand.
Alternatively, you can use corn starch (corn flour) and a few other ingredients for the custard flavour (see the FAQ later in this post).
Vegan-friendly puff pastry. A few brands of puff pastry are also accidentally vegan! Just check the ingredients to make sure it doesn't contain butter or animal products.
Dairy-free milk. I recommend choosing any rich and creamy milk that you enjoy drinking (for example, soy milk or oat milk).
Spreadable vegan butter (or vegan margarine) adds richness to the custard. I tested this recipe with Nuttelex spreadable butter rather than block butter because it's more accessible to people in Australia and New Zealand. Any brand of spreadable butter will work. Or use a vegan block butter for a firmer vanilla slice.
A complete list of ingredients, quantities and instructions are in the gray recipe card at the bottom of this post.
Preparing the puff pastry
First, we need to bake the pastry for our vegan vanilla slice!
We don't want the pastry to puff too much in the oven so I recommend baking it between two lined baking trays. The final pastry should be crispy and golden.
I've tried baking the puff pastry just on one baking tray and pressing it down afterwards. However, it's messier and doesn't always flatten!
Next, trim the puff pastry sheets to the size of your baking pan. The easiest way is to place your baking pan on top of your pastry. Then score and cut your pastry along the edges of your pan.
Some baking pans are not the same size on the bottom and top, so keep this in mind when you trim your pastry.
At this stage, I recommend lining your baking pan and placing one sheet of puff pastry at the bottom. When the custard is ready, we need to move quickly!
Make the vegan custard
The custard is easy to make and requires just a little mixing!
Combine your custard powder, sugar and just 1 cup of dairy-free milk to a large pot and mix until combined. This helps dissolve lumps in your powder and minimises any lumps in your final custard! Add the remaining milk, butter and vanilla then place your pot on your stovetop.
Then cook until the custard is smooth and thick. I recommend continually whisking the custard to prevent the custard from burning and turning lumpy.
When is the custard ready?
The custard is ready when it thickens to a thick pourable consistency. It should thickly coat the back of a spoon and leave little 'ribbons' if you lift the whisk. This should take about 15-25 minutes, depending on your stovetop.
If you're in doubt, cook the custard for a few minutes longer!
If there are lumps in your custard, don't worry. Use a stick blender to blend the mixture or quickly pour it through a fine sieve. I recommend using a stick blender because it's quicker and the custard sets quickly.
Assembling the vanilla slice
Once your custard thickens, assemble your vanilla slice as quickly as possible.
Pour your hot custard into your baking pan and smooth out the top if needed. Then press the remaining sheet of puff pastry on top. Set aside your vegan vanilla slice in the fridge for 4 hours or overnight.
Decoration options
I topped my vegan vanilla slice with a thick dusting of icing sugar (or powdered sugar). If you use icing sugar, it's easier to cut the slice and then dust it.
You can also top your vanilla slice with:
- Passionfruit icing (pictured)
- Pink-coloured icing.
If you spread icing on your vanilla slice while it's in the pan, when you remove it, your vanilla slice will bend from its weight and cause the icing to 'crack'. To prevent this, after you line your baking pan, I recommend placing a square of cardboard on top then assembling the vanilla slice on top. The cardboard will support the vanilla slice when you remove it.
Alternatively, you can remove your vanilla slice from the baking pan THEN ice the top.
Tips for cutting your vanilla slice
Don't be intimidated by this! The easiest way to cut a vanilla slice is to use a sharp serrated knife and a gentle sawing motion. This will keep the pastry intact and won't squish the custard filling!
If you'd like extra neat cuts, I recommend using a serrated knife to cut only through the top pastry layer. Then use a regular sharp knife to cut through the custard layer and bottom pastry layer.
Ingredient substitutions
Yes! However, you'll need to add a few other ingredients to mimic the flavour and colour of custard.
At the beginning of cooking, I recommend adding a pinch of turmeric (for colour) and, if you like, black salt (for an eggy flavour). Turmeric's colour intensifies as you cook it so try to not add too much. I also recommend increasing the sugar to 1 cup (200g).
For extra richness and flavour, you can also add soy or coconut milk powder, to taste.
I don't recommend using tapioca starch as it will make the custard slimy.
Yes, for a richer custard, substitute half of the milk with dairy-free pouring cream. It'll be more similar to the French vanilla slices from Australian bakeries (not a mille-feuille).
If you don't mind the flavour of coconut, you can also replace some of the milk with canned coconut milk.
Rice malt syrup and maple syrup will give the best flavour. However, they are liquid so will make a softer custard. Try increasing the custard powder to 1 ½ cups (170g). I haven't tested this but I think it will work.
Different flavours
This classic dessert is perfect as is! However, if you want something different, you can:
Make a vegan chocolate vanilla slice. Reduce the custard powder to 1 cup (115g), add ¼ cup (25g) cocoa powder and 100g chopped dairy-free chocolate to the custard.
Make a lemon custard slice. Replace ¼ cup (65g) milk with ¼ cup (65g) of fresh lemon juice, or to taste. Or check out my vegan lemon blueberry bars!
You can also use the custard to make a custard tart! Alternatively, check out my vegan custard tart and vegan egg tarts (Hong Kong style).
More bakery-style vegan desserts
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Vegan Vanilla Slice
Ingredients
Vegan Vanilla Slice
- 2 sheets frozen vegan puff pastry, thawed (note 1)
- 1 ¼ cups (145g) custard powder, (note 2)
- ¾ cup (150g) sugar, or caster sugar (or use 1 cup / 200g sugar if your custard powder doesn't have some sugar in it)
- 4 cups (1000g or 1L) dairy-free milk, such as soy or oat
- ½ cup (125g) vegan spreadable butter, or vegan block butter (note 3)
- 2 teaspoons vanilla paste, or vanilla extract
To decorate (see note 4 for icing options)
- ½ cup (50g) powdered sugar / icing sugar
Instructions
Prepare the pastry:
- Line 1 large baking trays with baking paper (parchment paper). Place the two sheets of frozen puff pastry on the trays and allow to thaw. If you can only fit one sheet of pastry on your baking tray, bake them after each other.
- Preheat your oven to 200°C (390°F) if using a convection oven. Or preheat to 180°C (350°F) if using a fan-forced oven.
- Place another sheet of baking paper on top of the pastry and another baking tray on top. Bake the pastry for around 20 minutes or until golden and baked through.
- Allow the pastry to completely cool down.
- Use a sharp serrated knife to trim the pastry to fit in your baking pan. I used a 23 cm (9-inch) baking pan. Alternatively, you may use a smaller baking pan such as an 8-inch (20cm). The custard layer of your slice will just be thicker!
- Line your square baking pan with baking paper with some overhanging. Place one of the trimmed pastry sheets on the bottom of your baking pan. Set aside.
Prepare the custard and assembly:
- Add the custard powder and sugar to a large pot and mix until combined. Add around 1 cup of milk and whisk until smooth and there are no lumps. Add the remaining milk, the spreadable butter and vanilla.
- Place the pot over medium-high heat and cook the custard for 15-25 minutes while whisking constantly. When the custard has thickened, cook it for another 3 minutes. The custard is ready when it thickly coats the back of a spoon and, if you lift your whisk, the custard should fall into thick 'ribbons'.
- If your custard has any lumps in it, quickly blend it with a stick blender or strain it through a metal sieve. This will temporarily make the custard runny, which is fine (it will thicken again later).
- Quickly pour the custard into your baking pan on top of the pastry. If needed, smooth the surface. Place the remaining pastry square on the top.
- Cover and chill the vanilla slice in the fridge for 4 hours or ideally overnight.
Cutting the vanilla slice:
- Remove the vanilla slice from the baking pan.
- Use a sharp serrated knife and a gentle 'back and forth' sawing motion to cut the vanilla slice into squares or rectangles. Dust the vanilla slice generously with icing sugar.
- Enjoy immediately! Store leftovers in an airtight container in the fridge for 3-4 days. The pastry will naturally soften over time. If you dusted your slice with icing sugar, it will dissolve overnight so I recommend dusting it again.
Notes
- Many brands of frozen puff pastry are accidentally vegan as they contain vegetable shortening instead of butter. However, double-check the ingredients of your pastry before you buy it.
- Similarly, many brands of custard powder are accidentally vegan. I used Foster Clarks custard powder but Bird's and the Woolworths brand also has a vegan-friendly custard powder. Double-check the ingredients to make sure it doesn't contain milk or egg solids. Alternatively, you can use the same amount in cornstarch / corn flour. I recommend adding a pinch of turmeric for colour. Check out the blog post for more details.
- I tested this recipe with Nuttelex Buttery as it's very accessible in Australia. However, you can use any spreadable vegan butter or a vegan block butter (for a slightly firmer custard).
- For passionfruit icing, combine 2 cups (300g) icing sugar, 3 tablespoons (45g) passionfruit pulp and ¼ cup (60g) melted vegan spreadable butter. For a classic pink icing, use the same ingredients but dairy-free milk instead of passionfruit pulp and add a few drops of pink or red food colouring. Add more sugar for a thicker icing or more liquid for a runnier icing. When the vanilla slice has set, remove it from the baking pan then ice the top. Chill it for another 30 minutes then cut and serve.
Nutrition
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Anthea, can I omit the vegan butter in this recipe?
Hi Andy, yes you can - the custard will just be softer, more jiggly and have less of a creamy mouthfeel. Hope that helps!
Because I’m slightly lazy could I use a pre made vegan custard (alpro/oatly)? And if so exactly how much would I need ?
Hi Ryan, alpro custard doesn't really keep shape so it won't really work. Or, you could cut individual serves of puff pastry, bake them and put alpro in between them, but it'll run out the sides after some time. Hope that helps!