Opera Cake

Opéra Cake
Lenôtre / Dalloyau Opéra Cake Recipe Inspired.

Makes one Finished 8x10-inch (20x28cm) Rectangle Cake or 12 1.5x4-inch (4x10cm) Individual Portions.
An opéra cake is a French dessert noted for its delicate, intensely flavored layers. There are many stories about the origins of this cake, known as both Clichy cake and Opéra cake, believed to have started out at the Paris Exposition Culinaire in 1903. However, another pastry shop, Dalloyau in the 50s, sold a very similar dessert (in honor of the Paris Opéra) although Gaston Lenôtre claims he invented the opéra cake as well. Whoever did it, this extraordinary cake will stick around for many years to come!. A traditional opera cake is made of thin layers of almond sponge cake (biscuit Joconde) completely soaked in coffee syrup, coffee buttercream, chocolate ganache and covered in a chocolate glaze. Its height goes between 1 to 1.5-inch (2.5 to 4cm). Opéra cake can be refrigerated for up to 5 days or frozen for weeks.

Joconde Biscuit (Almond Sponge Cake) Makes two 18x13-inch (46x33cm) Baking Trays.
5 ea. (150g) egg whites, at room temp
1gram cream of tartar or a few drops of lemon juice (this stabilizes the meringue)
1/4 cup (50g) granulated sugar
Almond Mixture
2.2 cups (250g) almond or hazelnut meal*
1.8 cups (250g) confectioner sugar
1/2 cup (80g) all-purpose flour
5 ea. (250g) large eggs
2.4 Tbsp (40g) unsalted butter, melted
*To make almond meal: in a food processor pulse sliced or silvered almonds until you get a fine flour, avoid blending it too long or you may get a paste-like butter.
In the bowl of a stand mixer fitted with the whisk attachment, beat egg whites along with cream of tartar and one-third of sugar 1.5 Tbsp (15g) on high speed and whip until stiffness is achieved adding remaining sugar gradually. Transfer meringue to a clean large bowl and set aside. In the same bowl ; no need to clean it, combine the powders with the eggs and beat on high speed for about 5 minutes until fluffy then add the melted butter. Gently, fold one-third of the meringue into the almond mixture and pour the all thing into remaining meringue and mix until just combined. Do not over work; it will deflate. Stick parchment paper on 2 upside down baking trays with a dot of batter on each corner. Spread the batter evenly into each 13x18-inch (33x46cm) baking tray.
Bake the sponges in a 450ºF (230ºC) preheated oven for about 7 minutes. Remove from oven and let cool 10 minutes and cover with parchment and flip biscuit over rack. Joconde biscuit can be kept a couple of days at room temperature, refrigerated a week or frozen for weeks; rolled into parchment and wrapped.

Coffee Buttercream (Crème Anglaise Style)
0.6 cup (150ml) whole milk
1 ounce (30g) French roast coffee beans
1/4 cup (50g) granulated sugar
3 ea. (60g) egg yolks
1/4 cup (50g) granulated sugar
1 Tbsp (5g) instant coffee or 1/2 Tbsp (7.5ml) coffee extract
11 Tbsp (165g) unsalted butter, at room temp
Bring milk, sugar and coffee beans to a simmer. Turn off the heat and let infuse for an hour or more. Meanwhile in a separate bowl, beat egg yolks and sugar to blend. Once infused, bring coffee milk back to boil, remove from heat and whisk milk gradually into the yolk mixture whisking constantly. Return custard to the stove, gently heat the mixture to just below the boiling point 185ºF (85ºC) it will thicken. Do not boil or the eggs will curdle. Check to see if it is the right consistency by holding a spatula that is covered with the custard and run your finger along the back of the spoon. If the streak remains without the cream running down through the streak, it is ready. Immediately remove from the heat and pass through a sieve (discard coffee beans) and over a mixer bowl. Beat the crème Anglaise with the instant coffee on high speed until has cooled to room temperature. Add the softened butter and whip until creamy on high speed. Buttercream Can be kept refrigerated for a week or frozen for up to 3 months.

Chocolate Ganache
5 onces (150g) dark chocolate couverture 66 / 70%
1/2 cup (110ml) heavy cream
2 Tbsp (30ml) light corn syrup or honey
2 Tbsp (30g) unsalted butter, cubed and at room temp.
Melt chocolate over a water-bath until just melted. Meanwhile warm up heavy cream with corn syrup and combine both mixtures and stir until completely smooth and add the cubed butter and continue stirring until smooth. Chill the ganache a bit until it has thickened enough and be like the buttercream texture. Ganache can be refrigerated for a week or frozen for weeks.

Chocolate Coating for Chablon*
2.6 ounces (80g) dark chocolate
0.8 Tbsp (8ml) neutral oil as peanut

* Chablon: the French term is ‘chablonner un biscuit’, which means to coat the surface of a biscuit with chocolate to reenforce the foundation of a cake and keeping its moisture in. It also adds up a pleasant texture.

Melt chocolate and oil and spread evenly on the bottom of one sponge cake and chill to set.

Coffee Syrup
1.2 cups (300ml) water
0.6 cup (130g) granulated sugar
1 Tbsp (5g) instant coffee or 1/2 Tbsp (7.5ml) coffee extract or 5 espresso or more to taste (reduce water is using espresso).
Bring all ingredients to boil and let cool to room temp before using. Can be stored 2 weeks in the refrigerator.

Chocolate Glaze Opéra
5 ounces (150g) dark chocolate couverture 64 / 70%
8 ounces (250g) coating dark chocolate (candy making & dipping dark melting wafers or pâte à glacer)
3 Tbsp (50ml) neutral oil as peanut
Melt all ingredients together over a water-bath until the mixture reaches 120ºF (50ºC) and cool to 95ºF (35/36ºC) before using.
Once the opéra cake is glazed, save chocolate glaze that has dropped on the bottom, rewarm it, strain it and store for later use.

Opéra Cake Assembly (without frame)

Use an upside down 9x12-inch (23x30cm) baking tray or something similar. Divide each cake sheet in half and make two 9x12-inch (23x30cm) rectangles; save 3 sponge sheets for the opera cake and save the 4th one for later use.
For the chablon, using a flat spatula, coat the surface of one sponge with the melted chocolate (for the bottom). Cover immediately with parchment in contact and flip over; chocolate side down and refrigerate to set. Remove from the fridge and brush generously with the coffee syrup (each layer of sponge must be well soaked in coffee syrup; that’s one of the main characteristic of the opéra cake).
Carefully, spread 1/3 of the coffee buttercream over the surface of the first sponge; it should not exceed 0.14-inch (3.5mm) thickness. Note that layers of the sponge cake, buttercream and ganache should have the same thickness.
Cover with the second sponge, brush with coffee syrup and spread the chocolate ganache evenly. Place the third and the last sponge cake on the top the ganache and do likewise with coffee syrup.
Chill cake until firm and spread evenly the third and the last coffee buttercream layer. To even the top cake perfectly, heat up a long offset spatula over the flame for a few seconds and smooth it out running your spatula back and forth.

Place cake the refrigerator over night (do not freeze before glazing or condensation will appear on the surface which will damage the chocolate glaze and its effect; chocolate does not like water in any circumstances).

Transfer cake on a draining grate and a place over a baking tray lined with plastic wrap to save drippings afterwards. Get the opera glaze ready at 95ºF (35/36ºC) and transfer glaze into a loaf pan (barely larger than the cake) and spread chocolate glaze over the cake from left to right in a slow but regular motion. Tap the tray to remove any air bubbles and immediately even the surface of the cake with a large offset spatula moving back and forth twice. The spatula should never be in direct contact with the chilled surface of the cake but rather up to 2 millimeters above the top chilled buttercream layer… don’t shake! This will remove excess chocolate glaze creating an awesome thin and barely firm top notch finish. Refrigerate opéra cake until top is set; about an hour before trimming off sides and serve. To make cuts look sharper bring a pitcher of hot water, dip the blade in between cuts, and wipe with a towel (a blow torch or stove flame can be used instead but heat the blade just a bit each time you make a cut. Decor: edible gold sheets and chocolate glaze writing (both are optional though) – Bon appétit!

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