Nanaimo Slice
A Nanaimo slice, more commonly called a Nanaimo bar, is a no-bake Canadian dessert square made of three distinct layers: a chocolate-coconut-graham crumb base pressed firm, a custard-flavored buttercream in the middle, and a thin melted chocolate topping that hardens into a shell. It's named after Nanaimo, British Columbia, where it was popularized in the 1950s and 60s, and it's served cold, cut into small squares since it's rich and dense rather than cakey.
Varieties
'Nanaimo bar' and 'Nanaimo slice' refer to the same dessert; 'slice' is more common in British and some Canadian usage for any layered bar cut into pieces. Variations swap the custard layer for mint, peanut butter, or matcha, and some bakeries add a shortbread or cheesecake layer, but the base crumb and top chocolate shell stay consistent across versions.
Buying tips
If buying premade from a bakery, check that the crumb base is held together with real butter rather than shortening, and that the chocolate top is a thin, snappy layer rather than a thick fudge-like coating, which usually signals a lower-quality substitute chocolate.
Substitutes
Instant vanilla pudding mix (dry powder) — 1:1 by volume
Closest swap for Bird's Custard Powder in the middle layer; gives a similar pale yellow color and sets to the same firm buttercream texture.
Cornstarch plus vanilla extract and a pinch of turmeric — 1 tbsp cornstarch + 1/2 tsp vanilla + tiny pinch turmeric per 1 tbsp custard powder
Turmeric replicates the yellow tint since cornstarch alone is white; use turmeric sparingly or it tastes bitter and earthy.
French vanilla instant pudding mix — 1:1 by volume
Slightly sweeter and more strongly vanilla-flavored than plain custard powder, so cut back the added sugar in the middle layer slightly.
Storage
Keep refrigerated in an airtight container, layered with parchment so the chocolate top doesn't stick to the lid. They hold well for up to two weeks refrigerated and freeze well for up to three months; thaw in the fridge rather than at room temperature so the layers don't separate.
How to use
Serve straight from the fridge, cut into small 1 to 1.5 inch squares since they're rich. Common on holiday dessert trays and cookie platters, and often given as edible gifts packed in a single layer box.
What it pairs with
Pairs well with black coffee or strong tea, which cut through the sweetness; also good alongside fresh raspberries or a small scoop of vanilla ice cream for a plated dessert.
Nutrition
Dense in sugar and butter across all three layers; a standard square runs high in calories and saturated fat for its size, which is why it's typically served in small portions rather than large cake-style slices.
FAQ
Why is it called a Nanaimo bar if the middle layer has no custard in it?
The 'custard' flavor comes from custard powder, a cornstarch-based mix tinted yellow and flavored with vanilla; it contains no eggs or dairy custard itself, it just mimics the color and flavor.
Can Nanaimo bars be made without custard powder at all?
Yes, plain vanilla buttercream works fine texturally, but the bars lose their signature pale yellow color and slightly different flavor note that custard powder provides.
Do Nanaimo bars need to be frozen or can they sit at room temperature?
They should stay refrigerated since the middle buttercream layer softens and can slide at room temperature after about an hour, especially in a warm kitchen.
Is there a gluten-free way to make the crumb base?
Yes, swap the graham cracker crumbs for gluten-free graham-style crackers or crushed gluten-free digestive biscuits; the coconut and cocoa powder in the base are naturally gluten-free.
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