Cashew Meringue Wafers, Praline Cream, and Dark Chocolate Ganache
1 cup whole toasted cashews [150 g]
1 cup confectioner's sugar [120 g]
Cashew Meringue Wafers:
10 large egg whites [300 g]
1 tsp cream of tartar [3.4 g]
1/2 cup granulated sugar [100 g]
1/3 cup powdered sugar [40 g]
2 cups whole toasted cashews [300 g]
1/4 cup cornstarch [30 g]
1 tsp vanilla extract [5 mL]
10 large egg yolks [200 g]
1/2 cup granulated sugar [100 g]
1/3 cup cornstarch [40 g]
3 cups milk [720 mL]
1 stick (8 tbsp) unsalted butter [113.6 g]
2 tbsp vanilla extract [30 mL]
2 tbsp rum (optional) [30 mL]
1 1/2 cups heavy cream [360 mL]
1/4 cup powdered sugar [30 g]
1/2 cup heavy cream [120 mL]
2/3 cup (4 oz) dark chocolate chips [113.2 g]
half of diplomat cream
1 cup of praline powder
Decoration and Topping:
1 cup whole toasted cashews [150 g]
1 cup chocolate sprinkles
a handful of dark chocolate chips as garnish
Cashew Meringue Wafers:
Separate 10 eggs into egg whites and egg yolks. Let the 10 egg whites and 10 egg yolks come to room temperature.
Place 2 oven racks on the lower and upper third positions in the oven. Preheat the oven to 350 degrees F. Put 4 cups of cashews in a sheet pan, and toast cashews in the upper third rack of the oven for 15 minutes, until they are golden brown. Set aside and let them cool.
Turn down the oven to 225 F (105 C). Line two large sheet pans (13x18 each pan) with parchment paper. Using a sharpie, draw two 8" diameter circles on the parchment paper so that there are 2 circles per pan. I draw the circles using the inside of the ring. It's okay if the circles touch a bit. There should be 4 circles total. Flip the parchment paper over so the side with the sharpie marks faces down, and away from the meringue wafers.
In a food processor, add in 2 cups of the toasted cashews, 1/3 cup powdered sugar, and 1/4 cup of cornstarch. Pulse till they are mixed and the cashews are very fine - looks like a powder.
In a stainless steel or glass mixing bowl, add in the 10 room temperature egg whites. Beat on low speed till the egg whites become frothy. Then increase to medium speed, add in the 1 tsp of cream of tartar, and mix it in. Then very slowly add in 1/2 cup of granulated sugar, a little at a time. When all the sugar has been added, increase the speed to high. Continue beating till you see very stiff peaks.
Carefully fold in the cashew powder mixture into the meringue, one third at a time, as well as 1 tsp of vanilla extract, just until it is evenly mixed.
Transfer this mixture into a pastry bag fitted with no metal tip. At a 45-degree angle, use the prepared circles on the parchment paper as a guide to pipe the batter into circular wafers that are 8 inches in diameter, using the pre-drawn circles as a guide. Pipe 2 circles per pan, for a total of 4 wafers. I'm piping all four circles, 1 ring at a time, going from. Just eye-balling it, try to end up with the same amount of batter in each circle.
Once all the batter has been piped, use an offset spatula or the back of a spoon to smoothen and flatten the tops of the wafers as much as possible.
Bake it in the preheated oven at 225 F (105 C) for 5 to 6 hours. Then turn off the oven heat but do not open the oven door. Leave the wafers in the turned-off oven overnight, for the wafers to continue drying out.
The low temperature (225 F) and long baking time (6 hours + residual oven heat overnight) is needed to remove all the moisture from the egg whites and create a hollow and dry wafer, without burning the outer layer of the meringue.
When the wafers are completely dry, they should come off the parchment paper quite easily. You can leave them at room temperature uncovered if you're not assembling the cake immediately. This will allow them to dry out more (which is preferred).
Line a small sheet pan with parchment paper.
Take 1 cup of the toasted cashews, and add them to a heavy-bottomed saucepan. Add in 1 cup of powdered sugar. Cook this over medium heat, stirring constantly, until the sugar begins to melt. The mixture will go through several stages, from a dry blend to one where the sugar forms little bubbles the size of peas. Continue cooking, stirring constantly so all of the sugar clinging to the cashews melt and are no longer in small clumps, until the mixture turns a tan brown and syrupy and the cashews make a popping sound. The whole process will take about 5 to 10 minutes. Keep a close watch and be careful not to overcook this mixture, otherwise it will take on a slight burnt flavor.
Quickly pour the mixture onto the parchment-paper lined sheet pan, trying not to touch the sides (which are not lined with parchment paper). The mixture will harden into a cashew brittle / praline. When the praline is cool, break it into pieces. Grind it to a fine powder in a food processor. (This cashew praline can be made days in advance and stored in an air-tight container at room temperature.)
In the bowl of your stand mixer, add in 10 egg yolks and 1/2 cup sugar. Using the whisk attachment, mix them together on high speed until it looks thick and lemon-yellow in color.
Add in 1/3 cup of cornstarch, and continue to mix until fully combined.
In a medium saucepan, heat 3 cups of milk over medium heat. Once the milk is hot and steaming, turn off the heat, and while whisking on medium speed with the whisk attachment, add about one-third of the hot milk into the egg mixture, and mix them on medium speed until combined. Then while vigorously whisking by hand, add this milk-egg mixture back into the steaming milk in the saucepan, and whisk them together until well combined. It's important to constantly whisk so the egg doesn't not get cooked and form lumps.
Turn the heat back on and continue cooking over medium heat, and bring it to a boil, whisking constantly, until the pastry cream is thickened. Once it starts to boil, continue heating for about one to two minutes. Transfer this mixture to a clean bowl and set it aside.
Whisk 1 stick (8 tbsp) of unsalted butter into the pastry cream, 2 tbsp of vanilla extract, and an *optional* 2 tbsp of dark rum until it is fully combined. If you prefer not to add alcohol, just leave out the dark rum. Transfer the pastry cream into a large mixing bowl. By now the pastry cream should have cooled down to warm and no longer extremely hot. Cover it with plastic wrap so that the plastic wrap is touching the surface of the pastry cream to prevent a skin from forming. Rest this pastry cream in the fridge overnight.
In a small microwave-safe bowl, add in 1/2 a cup of heavy cream. Microwave for 30 to 40 seconds, until the heavy cream is hot. You can also heat this in a saucepan on the stove if you don't have a microwave.
Add in 2/3 cup (4 oz) of dark chocolate chips. Whisk these together until the chocolate is completely melted and blended.
Set this aside until it comes to room temperature. It should have the consistency of a thick, spreadable, frosting. You can leave it in the fridge to speed up the thickening / cooling process.
Finishing Diplomat Cream and Dividing into Praline / Vanilla Creams:
Take the cooled pastry cream from the fridge, remove the plastic wrap, and whisk it to break up any lumps that may have formed and make it smooth again.
In the bowl of your stand mixer, add in 1 1/2 cups of very cold heavy cream, and 1/4 cup of powdered sugar. With the whisk attachment, whip this together until stiff peaks form. Carefully fold this whipped cream into the pastry cream, until they are smooth and well blended.
Divide this resulting diplomat cream (pastry cream with whipped cream folded into it) into two separate equal portions. Into one half, fold in 1 cup of the praline powder. This will be used for the inside layers of the cake. Leave the second half as is. This will be used for the outer layer of the cake and the top border decoration.
Assembling the Marjolaine Cake:
Take a cake board that's bigger than 8" (I like to use a 10" cake board), and place it on a revolving cake stand. Dab a little of the plain vanilla cream in the center of the cake board, so that cake doesn't slide around.
Place the first meringue wafer in the middle of the cake board. Spread about one-fourth of the chocolate ganache mixture on top of the wafer, forming a thin layer, then refrigerate this for about 10 minutes for the chocolate ganache to harden. Then spread one-third of the praline cream on top.
Place the 2nd meringue wafer on top, and repeat the steps, adding one-fourth of the chocolate ganache, refrigerating for 10 minutes, then adding one-third of the praline cream. Repeat this with the 3rd meringue wafer, one-fourth of the chocolate ganache, and then the last one-third of the praline pastry cream.
Add the 4th meringue wafer as the final wafer layer, then top with the last one-fourth of the chocolate ganache. Place this in the fridge for 10 minutes. Then frost the sides and the top of this cake with the vanilla cream. Be sure to save some of the vanilla cream for the top border of the cake. It's okay if you see a little chocolate mixed in with the vanilla cream, since the sides and top will be covered later on. Place the cake (and remaining vanilla cream) in the fridge to let the outer vanilla cream layer to firm up, for about 30 minutes.
Take 1 cup of the remaining toasted cashews, and roughly chop them into little pieces. Save about 1/4 cup of the chopped cashews and set them aside. Press the remaining chopped cashews into the vanilla cream so that they stick, along the top half of the cake's circumference. Let this rest in the fridge for 30 minutes for the vanilla cream to firm up again and let the toasted cashews on the side set.
Then similarly, take chocolate sprinkles and press them into the vanilla frosting so that they stick, along the bottom half of the cake's circumference. Clean up any excess cashews and chocolate sprinkles from the base of the cake. Let this rest in the fridge for 30 minutes for the frosting to harden up and the added decoration to set.
Attach a large petal tip on a piping bag, I use a #127. Fill the piping bag with the remaining vanilla cream. Create a border around the top circumference of the cake: with the wide-end pointing down, hold the tip at a 45-degree angle, pipe left to right in a zig-zag pattern, all the way around the cake.
Take the remaining 1/4 cup of chopped toasted cashews, and carefully place them in the center of the cake, in a mound in the center of the vanilla cream border. Garnish with a few dark chocolate chips for additional decoration.
Chill in the fridge for a minimum of 2 hours for the layers to set. This cake will keep in the fridge for up to 3 days, but the cashew wafers will slowly lose their crunchiness over time as they absorb moisture from the chocolate ganache and praline filling. Enjoy!