The earliest Nanaimo bar was found in Edith Adam’s cookbook from 1953. This version of the Canadian classic is served at Hearthstone Artisan bakery in Nanaimo, BC.
Place all ingredients in mixing bowl.
Blend together until fully incorporated.
Press evenly into lined 9×13 cake pan, set aside.
Cream together butter and custard powder until fluffy.
Add in icing sugar, milk and vanilla bean paste, beat again until smooth and fluffy.
Spread mixture evenly over base and put in the fridge while melting chocolate in the next step.
Chop up chocolate into small pieces.
Place chocolate in metal bowl with butter.
Set bowl over a boiling pot of water and stir with a heat proof spatula until melted, chocolate should be smooth and shiny.
Remove the pan from the fridge and pour chocolate over cold base and spread evenly on top.
Chill in the fridge for approx. 5 minutes until the chocolate is almost set. Score and cut the bars before they set.
Keep bars refrigerated until ready to eat.