Nanaimo Bars

Before you start

Nanaimo bars are a Canadian favorite named after the city of Nanaimo in British Columbia. They have three layers: a crumbly chocolate base of graham crumbs, coconut and walnuts; a thick, sweet middle of butter, powdered sugar and custard powder; and a thin layer of semisweet chocolate on top. Nothing goes in the oven.

The base is traditionally bound with an egg cooked into melted butter, sugar and cocoa over a double boiler. Cook it until it thickens and reaches 71°C (160°F) so the egg is safe and the base sets firm. Each layer then needs time in the refrigerator before the next goes on, or they blend together. Score the chocolate before it hardens completely so it does not crack when you cut.

Ingredients

• Base115 g (½ cup) unsalted butter
• 50 g (¼ cup) granulated sugar
• 30 g (⅓ cup) unsweetened cocoa powder
• 1 large egg — beaten
• 125 g (1¼ cups) graham cracker crumbs
• 85 g (1 cup) sweetened shredded coconut
• 60 g (½ cup) walnuts — finely chopped
• Custard layer115 g (½ cup) unsalted butter — softened
• 3 tbsp heavy cream or whole milk
• 2 tbsp custard powder — such as Bird's
• 250 g (2 cups) powdered sugar
• Chocolate top115 g semisweet chocolate — chopped
• 2 tbsp (30 g) unsalted butter

Method

1. Line the pan with parchment, leaving an overhang on two sides.
2. Set a heatproof bowl over a pan of barely simmering water. Melt the butter, sugar and cocoa together, stirring. Whisk in the beaten egg and cook, stirring constantly, for 2 to 4 minutes, until the mixture thickens to a pudding-like consistency and reads 71°C (160°F).
3. Take the bowl off the heat and stir in the graham crumbs, coconut and walnuts. Press the mixture firmly and evenly into the pan. Refrigerate for 30 minutes, until firm.
4. Beat the softened butter, cream and custard powder until smooth, then gradually add the powdered sugar and beat for 2 minutes, until light and spreadable. Spread it evenly over the chilled base and refrigerate for 30 minutes, until the surface is firm to the touch.
5. Melt the chocolate and butter together over the double boiler or in the microwave, stirring until smooth. Let it cool for 5 minutes so it is fluid but not hot enough to melt the custard layer.
6. Pour the chocolate over the custard layer and tilt the pan or use an offset spatula to spread it into a thin, even coat. Refrigerate for 10 to 15 minutes, until the chocolate is just set, then score it into 16 squares with a warm knife.
7. Refrigerate for about 45 minutes more, until fully firm. Lift out and cut along the score lines with a hot, dry knife, wiping it between cuts.

Tips for success

• Keep stirring while the egg cooks into the base; the edges of the bowl scramble first if left alone.
• Let the bars sit at room temperature for 10 minutes before cutting. Ice-cold chocolate shatters.
• Custard powder gives the middle its yellow color and vanilla flavor. Look for it in the British or baking section.

Substitutions

Custard powder

Use 2 tbsp instant vanilla pudding mix. The flavor is close; the color is paler.

Graham cracker crumbs

Digestive biscuit crumbs are a common Canadian and British alternative and work at the same weight.

Walnuts

Almonds or pecans work. For nut-free bars, replace them with 30 g more graham crumbs and 15 g more coconut.

Variations

Mint Nanaimo bars

Replace the custard powder with 1 tbsp more powdered sugar, ½ tsp peppermint extract and a drop of green coloring.

Peanut butter middle

Replace 40 g of the butter in the custard layer with creamy peanut butter.

Troubleshooting

Base is crumbly and will not hold

The egg mixture was not cooked thick enough, or the crumbs were not pressed firmly. Cook to 71°C (160°F) and pack the base hard.

The custard layer melted into the chocolate

The chocolate was too hot or the middle layer was not chilled enough. Chill until firm and cool the chocolate slightly first.

Chocolate cracks when cut

It was too thick or too cold. Score it while just set, and use a knife warmed in hot water and dried.

Storage

Keep Nanaimo bars covered in the refrigerator for up to 1 week and serve slightly cool. Freeze for up to 2 months, layered with parchment, and thaw in the refrigerator.

Safety notes

The egg in the base must be cooked to 160°F (71°C), as FDA advises for egg dishes; use a thermometer. Contains egg, milk, wheat and tree nuts.