How to Make Vanilla Slice. The Old-School Glossy Custard Slice

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This really is the best vanilla slice I’ve ever made. If you’re like me and not a fan of a dusted filo top, welcome because this is the old-school version with that chewy, bakery-style vanilla frosting that seeps between your teeth and catapults you back to primary school for a split second.

I can’t honestly claim the recipe. I first saw it on YouTube many years ago and lost the link but I did write it down in my trusted blue recipe book, and I did tweak the topping (original had a dusted filo top; I swapped in the glossy icing). The result? Proper nostalgia in every bite.

Table of Contents

Tips for the Best Vanilla Slice

Tempering your eggs matters

Always add a little hot milk to the yolks first, or you risk scrambled eggs.

Avoid a lumpy custard

Whisk well and consistently while cooking; if you do get tiny lumps, push the hot custard through a fine sieve while still warm.

For more information on perfecting custard, you can head over to my cooking guides.

Protect the custard

When it’s time to let the custard cool, press cling wrap onto the custard surface to prevent a skin as it cools.

Make Ahead

If you have the time, make the custard the day before. It gets better the next day, the custard firms and flavours settle.

Old-School Glossy Vanilla Slice

A nostalgic bakery-style vanilla slice with crisp puff pastry, a thick, creamy vanilla custard and the classic glossy white icing you remember from school canteens. No filo dusting here; just that chewy, old-school frosting that seeps between your teeth in every bite.

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Prep Time 15

Cook Time 40

Resting Time 6

Servings: 8 people

Course: Dessert

Ingredients Method

Ingredients

500 ml full-cream milk
130 g caster sugar
6 egg yolks
1 vanilla bean seeds scraped out
40 g plain all-purpose flour
30 g cornflour cornstarch
1 pack puff pastry you’ll use two sheets
Icing sugar + cold water for the glossy top

Method

Prepare the pastry:

Lay 2 sheets of puff pastry flat on a baking tray. Prick all over with a fork (docking) and sprinkle a little caster sugar over the top.
Place a wire rack over each sheet and then place two bread tins (or any heavy ovenproof tins) on top to weight the pastry so it doesn’t puff.
Bake at 200°C (390°F) for 15–20 minutes or until golden and cooked through. Remove weights and cool completely.

Make the vanilla custard (pastry cream):

Heat the 500 ml milk with the scraped vanilla seeds (and the pod if you like an extra hit of vanilla) just until it’s steaming. Don’t need a rolling boil, but almost. Remove from heat and discard the pod.
In a mixing bowl whisk the 6 egg yolks with 130 g caster sugar until pale and ribbony (about 1–2 minutes).
Add the plain flour and cornflour to the yolks and whisk until smooth.
Temper: pour a little of the hot milk into the yolk mixture while whisking (a few tbsp at first), then gradually add the rest until combined.
Return the mixture to the saucepan and cook on medium heat, whisking constantly. When it comes to a boil and thickens significantly (you’ll see it bubbling and holding on the whisk), keep whisking for another 30–60 seconds to cook out the raw starch. Remove from heat.
Pour the custard flat into a tray (this helps it cool evenly) and press cling wrap directly on the surface to stop a skin forming. Cool completely.

Assemble (two options):

Freehand (best for photos/presentation): Place one sheet of pastry on the serving board you plan to present on. Spread the cooled custard evenly on top, pressing gently and smoothing the sides with a spatula. Place the second pastry sheet on top and press down carefully to compact. Use a spatula or knife to tidy edges. If the sides are exposed, wrap cling wrap gently around the sides before chilling so the custard doesn’t dry out.
In a pan (neater, easier to cut): Line the base of a pan with a sheet of pastry (find a pan size that fits the pastry), pour and spread the custard, then top with the second pastry sheet. Chill in the pan; remove from pan to slice.

Top with that old-school glossy icing:

Put about 1 cup icing sugar into a bowl. Add cold water, 1 tbsp at a time, stirring until you reach a chewy, sticky consistency (not runny; it should spread but hold). You’ll need to eye-ball it. Add tiny amounts of water until it’s glossy and a bit tacky.
Spread evenly over the top pastry and refrigerate to set. Best flavour and texture is after 6 hours, ideally overnight.

FAQs: Vanilla Slice Recipe

1. How do I cut a vanilla slice cleanly?
Use a hot, sharp knife for the cleanest cuts: dip a long serrated or chef’s knife in very hot water, wipe it dry, then make each cut in one steady motion. Wipe the blade between slices with a hot towel (or re-dip) to avoid custard smearing. If using a serrated blade, use a gentle sawing motion rather than force. Cutting chilled (at least 6 hours) gives the best results.

2. Can I use store-bought custard or instant custard?
Anything is possible I guess

3. My custard is runny. How do I fix it?
Return it to a pan over medium heat and whisk until it thickens and comes to a slow boil. If it won’t set, whisk in a little extra cornflour slurry (½ tsp cornflour mixed with cold water), then heat and whisk until thick. Strain if needed to remove any tiny lumps.

4. Can I make this ahead? How long will it keep?
Yes. Best after 6 hours in the fridge, ideally overnight. Store covered in the refrigerator for up to 2–3 days. Keep the slice refrigerated after glazing.