Custard Slice

This super simple Custard Slice Recipe uses SAO Biscuits as “pastry” layers – shhh, don’t tell anyone!

The Recipe for SAO Custard Slice

This is a recipe our nans have had up their sleeves for a while.

My Dad remembers his mum making it a lot when he was younger.

While I don’t have a clear recollection of this slice, when I started eating it I felt like I’d had it before. Perhaps our tastebuds have their own memory!

As I mentioned already, it’s super simple to make – there’s the two SAO layers, a custard layer in between and an easy vanilla icing on top.

Ingredients for Custard Slice

All of the ingredient quantities are set out in the recipe card at the end of this post.

Here, though, I’ll run through the ingredients to give you an idea of what you might need to add to your shopping list:

• SAOs
• milk
• custard powder
• sugar
• butter
• vanilla extract
• icing sugar.

What is a SAO?

It’s a cracker biscuit created by Arnott’s in 1906.

The Australian Food Timeline explains the thinking around the name: “While some accounts say they’re named after boat, it’s widely believed that SAO stands for Salvation Army Officer. This was in honour of William Arnott’s son Arthur, who joined the Salvation Army.”

SAOs are regularly topped with cheese and tomato or vegemite for a snack or light lunch.

Here, though, we’re making custard slice!

How to make Custard Slice

You’ll need a 23 x 23cm square cake or baking tin.

Grease tin and line with baking paper, leaving excess on the sides to lift out slice once set.

Start by laying out SAOs on the bottom of the tray to form a complete layer (cut SAOs to fit if necessary).

Next, place all of the milk (except for 1/2 cup) in a saucepan and heat until almost boiling.

Combine the custard powder, sugar and remaining milk and add to milk in saucepan just before that milk boils. Whisk over heat for a few minutes or until custard thickens.

Take off the heat and stir in the butter and vanilla extract.

Allow the custard mixture to cool for a few minutes before pouring it onto the SAO biscuits.

Top with another layer of SAO biscuits. Again, cut SAOs to fit if necessary.

Place into the fridge to set.

Once cool, combine icing sugar, milk and vanilla extract for the vanilla icing and top the slice with the icing – spreading the icing with the back of a spoon to encourage an even layer of icing.

Place back into fridge and allow to set for at least a few hours, ideally overnight.

Dust with icing sugar if desired before serving.

Your custard slice should last for a couple of days in the fridge, but is best eaten within 12-24 hours.

Christmas Custard Slice

This is a great recipe for Christmas. So simple, yet you can make it look festive with a few sprinkles and a little holly.

Other recipes you’ll love

If you love this recipe, you might also like my recipes for Easy Vanilla Slice, Trifle, Bread and Butter Pudding, Chester Cake, Chinese Chews and Weetbix Marshmallow Slice.