Vanilla Custard Slice (Napoleon Slice) – Creamy, Flaky, and Irresistible

If you’ve ever bitten into a Vanilla Custard Slice, also known in many parts of the world as a Napoleon Slice, you already know why this dessert is so beloved. With layers of flaky puff pastry sandwiching a rich, creamy custard filling and finished with a sweet icing glaze, this dessert is indulgent, elegant, and surprisingly simple to make at home.

In this article, you’ll discover the origins of the vanilla custard slice, a step-by-step recipe, tips for success, delicious variations, and how to serve and store it. By the end, you’ll be ready to impress your family and guests with a bakery-style dessert made right in your kitchen.

What Is a Vanilla Custard Slice (Napoleon Slice)?

The Vanilla Custard Slice is a dessert composed of layers of puff pastry filled with a thick custard or pastry cream. In France, it is known as Mille-Feuille (which means “a thousand layers”) and in English-speaking countries, it’s often called a Napoleon Slice.

The combination of crispy pastry layers and silky-smooth custard cream makes it one of the most popular desserts across Europe, Australia, and beyond. Some versions are topped with powdered sugar, while others are finished with a glossy fondant icing, often decorated with a chocolate feathered pattern.

Ingredients for Vanilla Custard Slice

To make a classic custard slice, you’ll need:

2 sheets puff pastry (store-bought or homemade)
4 cups whole milk
¾ cup granulated sugar
6 large egg yolks
½ cup cornstarch
2 teaspoons pure vanilla extract
2 tablespoons unsalted butter
2 cups powdered sugar (for glaze)
2–3 tablespoons milk or water (for glaze)
Optional: 2 oz melted chocolate (for decorative swirl)

Step-by-Step Instructions

Step 1: Bake the Pastry Layers

Preheat oven to 400°F (200°C).
Place puff pastry sheets on lined baking trays. Prick all over with a fork to prevent excessive puffing.
Bake for 15–20 minutes until golden brown and crisp. Allow to cool completely.

Step 2: Prepare the Custard Filling

Heat milk in a saucepan until just simmering.
In a bowl, whisk egg yolks, sugar, and cornstarch until smooth.
Slowly pour hot milk into the egg mixture, whisking constantly.
Return mixture to saucepan and cook over medium heat, whisking, until thickened.
Remove from heat, stir in butter and vanilla. Cover with plastic wrap directly on the surface to prevent skin from forming. Let cool slightly.

Step 3: Assemble the Slice

Place one puff pastry sheet as the base.
Spread custard evenly over it.
Top with second puff pastry sheet.

Step 4: Add the Glaze

Mix powdered sugar with milk/water until thick but spreadable.
Spread glaze over top pastry.
(Optional) Pipe lines of melted chocolate across the glaze, then drag a toothpick through to create a feathered effect.

Step 5: Chill and Slice

Refrigerate for at least 4 hours (preferably overnight) to set.
Cut into squares or rectangles with a sharp knife.

Tips for Success

Chill before slicing: Custard must be fully set to cut clean pieces.
Sharp knife only: Use a serrated knife to cut through layers without crushing the pastry.
Prevent soggy pastry: Ensure pastry is fully baked and cooled before adding custard.
Use quality vanilla: Pure vanilla extract or paste elevates the custard flavor.

Variations

Chocolate Custard Slice – Replace vanilla with cocoa powder or melted chocolate in the custard.
Fruit Layer – Add fresh raspberries or sliced strawberries between layers for brightness.
Caramel Custard Slice – Swirl caramel into the custard for extra decadence.
Australian Vanilla Slice – Similar to the classic, but often thicker custard and sometimes topped with passionfruit icing.

Serving Ideas

Serve with tea or coffee for an afternoon treat.
Cut into bite-sized pieces for parties.
Dust with powdered sugar for a more rustic finish.
Pair with fresh berries to balance the richness.

Storage & Shelf Life

Store covered in the refrigerator for up to 3 days.
Do not freeze – puff pastry loses crispness once thawed.
Best enjoyed fresh after chilling overnight.

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