Nanaimo Slice
Nanaimo Slice is a classic Canadian tray bake made with three irresistible layers: a chocolate biscuit and coconut base, a creamy custard-flavoured filling, and a smooth chocolate topping. Rich, no-bake, and surprisingly easy to make.
Have you heard of Nanaimo Slice? Also often called Nanaimo Bars! This is one of many recipes I came across in my Mum’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 tray bake…
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 that you’ll hear many different stories about their origins depending on who you ask in the city of Nanaimo.
So, what is a traditional Nanaimo Bar?
Nanaimo Bars are a classic Canadian tray bake made up of three distinct layers: a chocolatey biscuit base, a creamy custard filling and a chocolate topping. Traditionally, the base is made with graham crackers, coconut and nuts, but digestive biscuits are much easier to find here in the UK and work perfectly in their place.
For me, though, it was a recipe from my Mum’s kitchen drawer that sent me on a path of perfecting my very own Nanaimo Slice recipe. My Mum has many little DIY recipe booklets; some from my own Granny that she put together with her friends from church or the Women’s Rural, and others collected from cafés and bakeries she worked with over the years.
The Nanaimo Slice recipe I found came from one of those café booklets. Like many homemade recipe collections, it was a bit of a mixed bag. Measurements switched between grams and ounces, instructions were often brief, and there wasn’t a photograph in sight. Making anything from them could be a bit of a challenge!
Regardless, I gave the recipe a go as my Mum remembered making it once or twice before. The base was absolutely delicious, but the filling was another story… Following the recipe word-for-word produced a lemony condensed milk filling that simply did not work. I was very disappointed and started looking into traditional Nanaimo Bar recipes to see where I’d gone wrong.
Turns out, a lemony condensed milk filling is not the norm when it comes to Nanaimo Bars. Not at all.
After comparing different Nanaimo Bar recipes and testing variations of my own, I settled on the custard filling you’ll find in this recipe. It keeps everything I loved about the original chocolatey base while delivering the flavour and texture most people expect from a traditional Nanaimo Bar.
If you’re a lover of no-bake tray bakes, Nanaimo Slice sits somewhere between a classic Tiffin and a Caramel Slice. It has the same easy-to-share appeal, but with the addition of a creamy custard layer that makes it feel a little different and somewhat more indulgent. And the best part is that there’s no baking required. Once the layers are made, all that’s left to do is let everything set before slicing.
Top Tips for Nanaimo Bars:
- Line Your Tin Well: Don’t be tempted to use a naked tin. Always line your tin with some greaseproof paper. This makes removing your Nanaimo Slice so much easier.
- Digestive Biscuits Work Perfectly: Traditional Canadian Nanaimo Bars use graham crackers, but digestive biscuits are the closest readily available alternative in the UK and give an excellent result.
- The Egg in the Base: This recipe uses an egg in the base, as is traditional for many Nanaimo Bar recipes. The egg helps bind the ingredients together, giving a firmer, less crumbly slice. As Nanaimo Slice is a no-bake tray bake, those who need to avoid undercooked eggs (eg. pregnant people) may prefer to leave it out, although the base may be slightly more crumbly as a result.
- Press the Base Firmly: Use the back of a spoon to press the base firmly into the corners of the tin. This helps the slice hold together when cut and creates a smooth base for the custard buttercream filling
- Set Layers Before Adding the Next: It can be tempting to rush ahead, but allowing the base and filling to firm up properly makes it much easier to create neat, even layers.
- Custard Powder Please: Custard powder gives Nanaimo Slice its distinctive flavour and colour. If you can’t get your hands on any, don’t worry. Instead, use the equivalent amount of Cornflour (corn starch) and a little vanilla extract. You can also add a smidgen of yellow food colouring if you want to replicate that custard colour.
- Chill Before Slicing: For the neatest slices, chill the Nanaimo Slice for a couple of hours before cutting. A sharp knife wiped clean between cuts will give the best results.
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Nanaimo Slice
INGREDIENTS
For the Base
- 115 g Block Margarine or Butter
- 55 g Soft Light Brown Sugar (Light Brown Sugar)
- 55 g Cocoa Powder
- 115 g Digestives Biscuits (Graham Crackers)
- 115 g Desiccated Coconut (Shredded Coconut)
- 115 g Walnuts (chopped)
- 1 Free-range Egg (beaten)
For the Filling
- 100 g Block Margarine or Butter
- 4 tbsp Double Cream (Heavy Cream)
- 3 tbsp Custard Powder (see below for substitutions)
- 250 g Icing Sugar (Powdered Sugar)
For the Topping
- 200 g Dark Chocolate
- 2 tbsp Block Margarine or Butter
EQUIPMENT
INSTRUCTIONS
For the Base
- Line a 20x20cm (8-inch) tin 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 tin, 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 tin, at least score the chocolate in the tin to avoid the filling pressing out whilst cutting.
IMPORTANT NOTE:
All my recipes are developed using a digital scale and the metric system (grams and millilitres). Cup measurements are available as a conversion but these, unfortunately, won’t always be as accurate. For best results, I always recommend baking with a digital scale.
NOTES
Egg Size:
When it comes to eggs, I always buy the Mixed-weight Free-range Eggs. Generally speaking, egg size doesn’t make a huge difference in most baking, unless you are using sizes that lean into the extremes. But with that in mind, medium-sized eggs are probably the best option if you are unsure what size eggs to use.Storage:
Store Nanaimo Slice in an airtight container in the fridge for up to 5 days. The custard filling and chocolate topping keep best when chilled.Freezing:
Nanaimo Slice freezes well. Cut into portions, place in an airtight container and freeze for up to 3 months. Defrost in the fridge overnight before serving.- Digestive Biscuits: Traditionally, Nanaimo Bars are usually made with graham crackers, but digestive biscuits are a readily available alternative in the UK and work perfectly in this recipe.
- Nuts: Walnuts are traditional in Nanaimo Slice, but pecans can be used instead. Or, if you prefer, you can omit the nuts altogether, although the texture of the base will be slightly different.
- Egg in the Base: This recipe uses an egg in the base, as is traditional for many Nanaimo Bar recipes. The egg helps bind the ingredients together, giving a firmer, less crumbly slice. As Nanaimo Slice is a no-bake tray bake, those who need to avoid undercooked eggs may prefer to leave it out, although the base may be slightly more fragile
- Chocolate: Dark chocolate helps balance the sweetness of the custard filling, but milk chocolate can be used if you prefer a sweeter Nanaimo Slice.
- Custard Powder: Birds Custard Powder is a staple in UK homes, but it isn’t available everywhere. A good substitution is actually some Vanilla Jello Powder! Alternatively, you can use corn flour (corn starch) and add a little vanilla extract for a custard-like flavour. And for the full custard-powder-effect, you could even add a smidgen of yellow food colouring – although that’s purely optional!
Tried this recipe?
Tag @bakingwithgranny or use the hashtag #bakingwithgranny!Frequently Asked Questions:
Nanaimo Slice, also known as Nanaimo Bars, is a traditional Canadian tray bake made with three layers: a chocolatey-nutty biscuit base, a custard-buttercream filling and a chocolate topping. Unlike many tray bakes, it requires no baking and is chilled until set.
Nanaimo Slice gets its name from the city of Nanaimo in British Columbia, Canada. The first known published recipes appeared in the early 1950s, although it’s believed the tray bake may have existed long before then.
Custard powder is what gives the filling its distinctive flavour and colour, but can be swapped out for the equivalent amount of cornflour (corn starch) and some vanilla extract – you can also add a little yellow food colouring for that distinctive custard colour. Alternatively, vanilla Jell-O powder makes a good substitute.
Yes! Traditional Nanaimo Bars are usually made with graham crackers, but digestive biscuits are much easier to find in the UK and make an excellent substitute.
Chocolate can become quite firm when chilled. For cleaner slices, leave the Nanaimo Slice at room temperature for 10-15 minutes before cutting, score the top of the chocolate where you plan to cut, and be confident when it comes to cutting your slices.
Many traditional Nanaimo Bar recipes include an egg in the base, and this recipe does too. The egg is mixed into warm melted ingredients, which cooks it to some degree, but as this is a no-bake tray bake, it may not be suitable for those who need to avoid undercooked eggs.
Free-from & Vegan:
Gluten-free Options:
To make a gluten-free Nanaimo Slice, simply replace the digestive biscuits with your favourite gluten-free alternative. Be sure to also check that your custard powder, cocoa powder and chocolate are certified gluten-free, as ingredients can vary between brands.
Nut-free Adjustments:
Although walnuts are used in the base, you can omit them to make nut-free Nanaimo Bars.
Dairy-free Swaps:
The butter in both the base and filling can be replaced with a dairy-free block margarine. You’ll also need to use a dairy-free dark chocolate for the topping.
Egg-Free Adaptions:
You can omit the egg in the base of Nanaimo Slice, but as it works as a binder, the base may be a little crumblier as a result.
Vegan Substitutions:
For a vegan Nanaimo Slice, replace the butter with a vegan block margarine and use a dairy-free dark chocolate. The egg in the base can be omitted, although the base may be a little more crumbly as the egg helps bind the ingredients together. You’ll also need to ensure your custard powder is suitable for vegans.
Allergy Disclaimer & Resources:
Any advice or suggestions to make recipes “free-from” or vegan are purely suggestions. Please double-check all packaged ingredients individually, taking extra caution when baking for those with allergies or intolerances.
For official guidance on food allergies, please see Food Standards Agency (food.gov.uk) | For more info on coeliac disease, please see Coeliac UK (coeliac.org.uk) | For more info on a vegan diet, please see The Vegan Society (vegansociety.com)
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?
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!
I have to make these they look delicious