Nanaimo Slice

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Nanaimo Slice recipe from Baking with Granny. Nanaimo Bars traybake.

Have you heard of Nanaimo Slice? Also often called Nanaimo Bars! This is one of many recipes I came across in Granny’s repertoire that left me intrigued. My first question…how do you even pronounce it?!

A quick Google search told me that it is pronounced “nuh-nai-mow“. And that it is also a city in Canada! Which takes us nicely to the origin of this traybake.

The first known recipe for Nanaimo Bars appeared in the Nanaimo Hospital Cookbook in 1952, and was simply called “chocolate squares”. Only a year later, a similar recipe was published in another recipe book (Edith Adam’s Cookbook) but this time using the name “Nanaimo Bar”. Despite these being the first known publications of the recipe, it’s believed that Nanaimo Bars have probably been around a whole lot longer, with it being said you will be told many varying origins, depending who you actually ask in the city of Nanaimo.

Nanaimo Bars, a Canadian recipe from Baking with Grany.

For me though, it was a recipe from Granny’s kitchen drawer that sent me on a path of perfecting our very own Nanaimo Slice. Granny has many little DIY recipe booklets; some from my own Granny, that she had put together with her friends from church or the Women’s Rural; and some that she received from the cafes and bakeries she worked with, many years ago.

The traybake recipe booklet that I first came across a Nanaimo Slice recipe was from a café that Granny worked with, once upon a time. Like most of these little DIY booklets, this one was a very amateur affair… The recipes come in varying units of measurement (grams and ounces, often used in the same recipes), sometimes sketchy instructions and no photos, so result are always a surprise!

Regardless, I gave the recipe a go as Granny remembered making it once or twice, and although my first attempt had a wonderfully delicious base, the filling was a disaster! That was having followed the recipes instructions and quantities to-the-letter for a lemony, condensed milk filling. I was very disappointed. Wondering where I went wrong, I looked into different Nanaimo Bar recipes.

Turns out, a lemony, condensed milk filling is not the norm when it comes to Nanaimo Bars! Not at all.

Nanaimo Slice recipe from Baking with Granny. Nanaimo Bars traybake.

So what is a traditional Nanaimo Bar?

Nanaimo Bars are instantly recognisable by their speckled biscuit base, yellowy cream filling and shiny chocolate topping. The base being made up of gram crackers (or in this case, digestive biscuits), coconut, nuts and chocolate. The filling is a custard icing, but don’t worry, it’s exceptionally easy to make. And the top is a beautifully rich dark chocolate, to finish this already tooth-achingly sweet treat.

Once I knew the recipe I was working on had gone completely off-piste with the filling, I was able to experiment with the perfect custard icing, and the chocolate to filling/base ratio. And I think this recipe now has it spot on, if I do say so myself!

Nanaimo Bars recipe from Baking with Granny.


Margarine or Butter
You’ll actually need a little of this for all 3 aspects of this recipe: the base, the filling and the topping. In the base it adds some moisture and helps act as a binder for the dry ingredients. In the filling it will be one of the main components of the custard icing, as really it could also be described as a custard buttercream. And in the topping, it helps thin out the chocolate a little, making it much easier to cut.
It’s personal preference whether you use margarine or butter; I like margarine as a way to omit the dairy. But if you are using margarine be sure to use a block margarine, as opposed to the spreadable versions.

Soft Light Brown Sugar
This is to add a bit of sweetness to your base. Soft light brown sugar is great for adding a slightly more subtle sweetness (compared to white sugars) but without having too much of a caramel flavour (compared to dark brown sugars). If you don’t have any soft light brown sugar to hand though, you can of course substitute for a different sugar, if you don’t mind the extra sweetness or slight change in flavour.

Cocoa Powder
Whilst dark chocolate is used in the topping for Nanaimo Slice, it’s cocoa powder which gives the chocolate flavour to the base.

Digestive Biscuits
Traditionally it would be Graham Crackers that would be used in a Nanaimo Bars but as we are in the UK, the go-to substitute of digestive biscuits is used instead.

Desiccated Coconut
Having coconut in the base seems to be a must in every Nanaimo Bar recipe I’ve encountered. Some used desiccated, some use flaked. I’ve opted for desiccated for a stronger flavour and a more even texture.

The jury is out on the “right” nut to have in Nanaimo Slice, with variations between walnuts, almonds, hazelnuts… I have gone with walnuts though, partly because they’re my favourite, partly because their subtle buttery flavour, and soft bite compliment everything else going on perfectly.

This was an ingredient that caught be by surprise but in the interest of keeping true to the original bake, I’ve decided to include it. Most (if not all) Nanaimo Bar recipes seem to include an egg in their base.

And yes, that is correct, the egg is not cooked. Granny assures me that the residual heat from the rest of the base should be enough to “cook” the egg, whilst mixing it into the base mixture. However, I don’t believe you can ever be too cautious with these things, and because of the addition of the egg and not being able to tell if it has been cooked completely, I would advise against serving Nanaimo Slice to anyone with a compromised immune system, children under 12 months, and pregnant people. Especially if you are outside the UK and using eggs that haven’t had a Red Lion stamp.

Custard Powder
The secret ingredient in the custard icing filling! You want to be using good old fashioned Birds Custard Powder, the kind your Granny would use to accompany any kind of pudding on Christmas day. Not only does it give the filling that familiar vanilla custard flavour, it also gives it a warm yellow hue.

Double Cream
With the addition of the custard powder in the filling, the double cream helps counter some of the extra thickness this can add. Plus it gives a slightly richer flavour too.

Icing Sugar
The last ingredient to bring the filling together, giving it that sweet flavour and when mixed just-right with the butter/margarine, that perfectly light texture.

Dark Chocolate
To finish off our Nanaimo Slice, a beautifully rich dark chocolate layer. I’d recommend a decent quality dark chocolate, as you’re going to mix through a little butter/margarine to help thin it down a bit; the reason being so it is easier to cut – there’s nothing worse than trying to cut solid chocolate and all your custard icing filling squidging out the sides! And by using a decent dark chocolate, the flavour won’t be too compromised by the addition of the butter/margarine.

Nanaimo Slice recipe from Baking with Granny. Nanaimo Bars traybake.

Love this? Try this:

Nanaimo Slice recipe from Baking with Granny. Nanaimo Bars traybake.

Nanaimo Slice

5 from 2 votes
Servings: 12 slices


For the Base

For the Filling

For the Topping


For the Base

  • Line a 9x12 inch tray with greaseproof paper and set aside.
  • In a medium-large pan, melt the margarine/butter, soft light brown sugar and cocoa powder over a low heat. Meanwhile, crush the digestive biscuits, either by pulsing in a blender or placing them in a freezer bag and hitting with a rolling pin.
  • Once the margarine/butter, sugar & cocoa powder have melted, add the crushed digestives, desiccated coconut & walnuts, and mix until combined. Add the beaten egg and mix through.
  • Transfer the base mixture to your pre-lined tray, and press evenly & into the corners of the tray with the back of a spoon. Leave to cool before transferring to the fridge to set, ideally for a couple of hours.

For the Filling

  • In a large bowl, sift the icing sugar and custard powder, before adding the margarine/butter and double cream Beat together until light and fluffy.
  • Remove the base from the fridge and spread the custard icing evenly across the top, right into the corners. Return to the fridge whilst you prepare the topping.

For the Topping

  • Melt the dark chocolate over a bain-marie or in short bursts in the microwave. Add the margarine/butter and stir until melted through.
  • Pour the chocolate mixture over the filling, spread it evenly & right into the corners. Place back into the fridge to set, ideally for a couple of hours.
  • When ready to serve, cut the Nanaimo Slice into bars, ideally whilst still in the tray. If it isn't possible to cut in the tray, at least score the chocolate in the tray, to avoid the filling pressing out whilst cutting.
Tried this recipe?Tag @bakingwithgranny or use the hashtag #bakingwithgranny!
Nanaimo Slice Recipe from Baking with Granny. Traditional nanaimo bars, made with chocolate, walnuts and custard buttercream.
Nanaimo Bars recipe from Baking with Granny.

8 Responses

  1. 5 stars
    This recipe looks delicious. I have to make many tray bakes for small local events/ coffee mornings etc BUT they have to be NUT FREE. Do you think it would be possible to omit the nuts in the base? Should I replace with extra digestive biscuits?

    1. Why not substitute with those small marshmallows you find in hot chocolate & Rocky Road, with halved glacé cherries? I have a problem with nuts in my food, because my cancer medication has made my mouth very sore & loosened a couple of my teeth, so I’m turning to marshmallows. My great- nieces & nephews loved them, I believe. I would definitely go with nuts if I could, but I really daren’t!

  2. My mother and her friends made these regularly. I understand they are a Canadian thing. Everyone here is familiar with them. You can even buy them in stores. The home made ones are better

    1. I haven’t tried this but for a lemony filling as Birds Custard Powder is basically cornflour, I’d swap it out with the cornflour and add finely grated lemon zest – quantity up to you and how lemony you want it! Good luck!

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Hello, I’m Amy, the voice-behind and creator-of Baking with Granny.

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