Emelia Jackson’s foolproof vanilla slice is easier to make than you might expect

Name: Emelia Jackson’s foolproof vanilla slice is easier to make than you might expect
Cook time: 30 min
Yield: 12 squares
Cuisine: French
Ingredients: 2 sheets frozen butter puff pastry (I use Careme), thawed; ruby grapefruit peel, cut into thin strips, to garnish

Finished with a ruby glow, this zesty twist on the country bakery classic is more “modern chic”, less “sugar coma”.

Emelia Jackson

March 6, 2026

Using store-bought puff pastry makes this vanilla slice a simple weekend project.Armelle Habib; STYLING: Lee Blaylock

easyTime:< 30 minsMakes:12 squares

The vanilla slice is a nostalgic country bakery classic: a thick, wobbly slab of creamy vanilla-flecked custard sandwiched between layers of golden pastry and finished with a sweet glaze. Yet perfecting that balance of flaky pastry and smooth custard can feel like a feat.

By using high-quality store-bought puff pastry and a pastel-pretty ruby grapefruit icing, it becomes a refreshingly simple weekend project – elegant enough to anchor any afternoon tea.

Ingredients

2 sheets frozen butter puff pastry (I use Careme), thawed
ruby grapefruit peel, cut into thin strips, to garnish

VANILLA CUSTARD

2 egg yolks
190g caster sugar
60g cornflour
100g custard powder
1 litre full-cream milk
300g thickened cream
2 tsp vanilla bean paste
50g unsalted butter

RUBY GRAPEFRUIT GLAZE

30g unsalted butter, melted
200g icing sugar
zest of ½ a ruby grapefruit
40ml ruby grapefruit juice (about ¼ of the fruit)
¼ tsp citric acid
1 drop red food colouring

Method

Step 1
Preheat oven to 200C fan-forced (220C conventional).
Step 2
To ensure the pastry remains flat and crisp, place each sheet on a separate lined baking tray, cover with a second sheet of baking paper, and weight it down with another tray. Bake the sheets for 18-20 minutes until deeply golden, then remove from the oven and set aside to cool completely.
Step 3
In a large saucepan, whisk the egg yolks, sugar, cornflour and custard powder until combined. Gradually whisk in the milk, cream, and vanilla paste until smooth. Cook over medium heat, stirring constantly, until the custard thickens and comes to a boil; this is essential to cook out the starch and ensure a firm set. Stir in the butter until it has melted, and the custard is glossy.
Step 4
Place one baked pastry sheet on the base of a lined 20cm-square baking tin, trim to fit if necessary, then pour over the warm custard, and spread evenly. Top with the second pastry sheet and refrigerate until fully set, ideally for four hours or overnight.
Step 5
To make the grapefruit glaze, whisk the melted butter with the icing sugar, grapefruit zest and juice until thick and pourable. If any lumps remain, an immersion blender is your best friend for a perfectly smooth finish. Stir in the citric acid and a drop of red food colouring to bring the ruby hue to life.
Step 6
Spread the glaze over the chilled slice and return it to the fridge for 2-4 hours until firm.
Step 7
To serve, using a sharp serrated knife, cut into 12 neat squares, wiping the blade clean between each cut, and garnish with thin strips of grapefruit peel.

Techniques of the month: Perfectly set custard and neat slicing

Perfectly set custard

Cooking the custard over medium heat while stirring constantly is the best way to prevent lumps and guarantee a silky, firm set. If any lumps do form, simply pulse them out with an immersion blender before assembly.

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For the crispiest results, let the custard cool slightly before pouring to avoid steaming the pastry.

Neat slicing

When you’re ready to serve, use a sharp serrated knife to gently saw through the delicate top layer before pressing down to slice through the base.

Ensure the slice is thoroughly chilled and wipe your blade between every cut for a bakery-standard finish.

Tips for success

Use good-quality frozen puff pastry and thaw it fully before baking.
Don’t rush the custard cooking – it needs to be thick enough to coat the back of a spoon.
You can swap out the ruby grapefruit for any citrus you love. Lemon, orange, blood orange and yuzu all work beautifully. Otherwise, stick with tradition by using passionfruit pulp.
Use a serrated knife or sharp chef’s knife, and wipe it clean between cuts to ensure each square has neat edges.