These easy Nanaimo Bars are no-bake layered bars with a chocolate graham cracker base (without coconut), a vanilla custard buttercream filling, and topped with a blanket of luscious chocolate. For an authentic version, just add the coconut back in the base. Nanaimo bars are a rich and creamy, smooth and crunchy treat!
2½cups(300grams)graham cracker crumbs, about 18 to 20 sheets, see Recipe Notes
For the vanilla custard buttercream filling
2cups(227grams)powdered sugar, sifted
½cup(114grams)unsalted butter, at room temperature
2tablespoons(20grams)custard powder, sifted, see Recipe Notes
2 to 3tablespoons(2tablespoon)heavy cream, or milk
For the topping
3ounces(85grams)dark chocolate wafers, or solid chocolate bar, chopped (½ cup), see Recipe Notes
1tablespoon(15grams)unsalted butter
Instructions
Spray an 8- x 8-inch baking pan with baking spray, then line the pan with parchment paper, leaving a 2-inch overhang. Lightly spray the parchment paper and the sides of the pan. Set aside.
Make the chocolate graham cracker base: Melt the butter in a large microwave-safe bowl for 1 minute in 30 second intervals. Whisk in the cocoa powder, sugar, and salt.
Gently raise the temperature of the beaten egg by spooning a small amount of the chocolate mixture into the egg, then gradually add the egg mixture back into the chocolate, whisking constantly. This process is called tempering the egg.
Heat the chocolate mixture in the microwave for 20 seconds at 40% powder until it reads at least 150 °F on a digital thermometer to gently cook the egg, about 1½ to 2 minutes (any higher and the egg can scramble). Alternately, heat the chocolate and egg mixture over a saucepan of gently simmering water until the mixture is slightly thickened and the temperature is at least 150 °F on a digital thermometer. You can skip this cooking step entirely if you’re using pasteurized egg whites instead of a beaten egg.
Fold the graham cracker crumbs into the chocolate mixture, stirring until everything is well coated.
Press the crumb mixture firmly into the baking pan. A piece of plastic wrap helps to keep it from sticking to your fingers. Chill the base in the freezer while you make the filling, about 10 minutes.
Make the vanilla custard buttercream filling: In the bowl of a stand mixer fitted with the paddle attachment (a large bowl if using a hand mixer), combine the powdered sugar, butter, custard powder, and 2 tablespoons of heavy cream. Slowly mix on Low speed to start, then increase the speed to Medium and beat until the filling is smooth, light, and fluffy. Add an additional tablespoon of heavy cream if necessary to achieve the correct consistency.
Remove the base from the freezer and spread the filling on top, smoothing with a small offset spatula. Chill the pan (this time in the refrigerator) for at least 30 minutes to firm up the filling.
Make the chocolate topping: In a small microwave-safe bowl, melt the chocolate and butter together in the microwave for 1 to 1½ minutes in 30 second intervals. Stir until smooth.
Remove the pan from the refrigerator and spread the chocolate over the filling, again smoothing with a small offset spatula. Work quickly as the cold filling can cause the chocolate to set quite fast.
Return the pan to the refrigerator and chill until the chocolate is completely set, about 1 to 2 hours.
When the topping is set, remove the slab from the baking pan using the parchment paper as a sling and transfer to a cutting board. Peel off the parchment paper.
Using a serrated knife, slice the slab into 2- x 2-inch squares.
Storage instructions: Store the bars covered in the refrigerator for a week, or freeze individually wrapped bars in an airtight container for up to 3 months.
Recipe Notes
Keep in mind that if you're using a non-pasteurized egg, you should avoid serving Nanaimo Bars to pregnant women, small children, and people who have compromised immune systems since the egg isn’t fully cooked to 160°F recommended by the FDA. You can substitute 3 tablespoons (42 grams) of pasteurized eggs whites instead of a beaten egg to avoid this problem entirely.If you want a more traditional Nanaimo Bar base, add 1 cup shredded sweetened coconut flakes and decrease the graham cracker crumbs by ½ cup (71 grams, about 3 to 5 sheets).Custard powder is cornstarch flavored with vanilla powder. You can substitute 2 tablespoons cornstarch plus 1 teaspoon vanilla for the custard powder if you wish.The dark chocolate (either from chocolate wafers or a solid chocolate bar) and dark chocolate cocoa power used here give these bars a deep rich chocolate flavor. You can use semisweet and regular unsweetened cocoa powder if you prefer.For thinner bars, this recipe can be made in a 9- x 13-inch baking pan. Just double the ingredients for the frosting and use ⅔ cup chocolate melted with 2 tablespoons of butter.