Lemon Opera Cake

By Sarah-Lyn

Ingredients

• Joconde (Cake Layer)
• 6 large egg whites, at room temperature
• 2 Tbsp. granulated sugar
• 2 cups almond meal/flour
• 2 cups icing sugar, sifted
• 6 large eggs (Note: You will need a total of 12 eggs but you will not use 6 of the egg yolks)
• 1/4 cup plus 2 Tablespoons millet flour
• 2 Tablespoons sweet rice flour
• 3 Tbsp. unsalted butter, melted and cooled

Details

Servings 10
Adapted from glutenfreemommy.com

Preparation

Step 1

Preheat oven to 400 degrees. Grease a 12 x 17 jelly roll pan (remember I had to change pan sizes from original recipe). You can also line with parchment paper but I did not have any handy. I also greased a small cake pan to pour the extra batter because of my pan dilemma. In your stand mixer (with whisk attachment), beat egg whites until soft peaks form and add the 2 Tablespoons sugar. Beat until stiff and shiny. If you don’t have another bowl for your stand mixer, pour egg mixture into separate bowl and clean for the next step. Fit your stand mixer with the paddle attachment and mix the 6 whole eggs, powdered sugar, and almond meal together for about 3 minutes. Once fluffy, add your flours and xanthan gum. Combine but do not overmix. Using a rubber spatula gently fold in the egg mixture and stir in the melted butter. Pour most of the batter into the jelly roll pan (3/4 full) and pour remaining batter into a small cakepan. I used the joconde from the small cake pan as a taste test because I did not want to continue with the recipe if I did not like the results of the cake. However, the cake tasted great so I moved on. Bake for about 10-14 minutes. Cool for 10 minutes. Loosen the edges and unmold on a piece of parchment paper. Let cakes cool to room temperature.

Lemon Syrup

½ cup water

⅓ cup granulated sugar

2 Tablespoons freshly squeezed lemon juice

DIRECTIONS:

Stir all the syrup ingredients together in the saucepan and bring to a boil. Remove from heat and let the syrup cool to room temperature.

Lemon Butter Cream Frosting

1 cup granulated sugar

¼ cup water

seeds of one vanilla bean (split a vanilla bean down the middle and scrape out the seeds) or 1 tbsp. pure vanilla extract

1 large egg

1 large egg yolk

1¾ sticks unsalted butter, at room temperature

1 Tablespoon lemon zest

1/4 teaspoon lemon extract

2 Tablespoons lemon juice

DIRECTIONS:

Combine the sugar, water and vanilla and lemon extracts in a small saucepan and warm over medium heat just until the sugar dissolves.
Cook the syrup until the syrup reaches 225◦F on a candy or instant-read thermometer. Once it reaches 225 degrees, remove the syrup from the heat.

While the syrup is heating, begin whisking the egg and egg yolk at high speed in the bowl of your mixer using the whisk attachment. Whisk them until they are pale and foamy.

Reduce the mixer speed to low speed and begin slowly pouring the syrup into the egg mixture- be careful not to get any of the syrup on the sides of the mixer bowl. Some of the syrup will spin onto the sides of the bowl but don’t worry about this and don’t try to stir it into the mixture as it will harden!
Raise the speed to medium-high and continue beating until the egg mixture is thick and the mixture is cool to the touch. This will take about 5 minutes.

While you are waiting on the egg mixture to thicken, mash the softened butter in a bowl with a fork. Once the egg mixture becomes thick, add the butter in small chunks until is all incorporated. The buttercream mixture will be thick and shiny at this point.
Mix in 2 Tablespoons freshly squeezed lemon juice and 1 Tablespoon lemon zest and beat for an additional minute or so.

Refrigerate the buttercream. Go back and stir it occasionally until it is firm enough to be spread on the cake- this will take about 30 minutes. Note: You can not use salted butter in this recipe!

Lemon White Chocolate Mousse

7 ounces white chocolate

1 cup plus 3 tbsp. heavy cream

1/4 cup freshly squeezed lemon juice

DIRECTIONS:

Melt the white chocolate and the 3 tbsp. of heavy cream over a double boiler. Stir until smooth. Add the lemon juice and combine. Set aside to cool completely. In the bowl of a stand mixer (you have to wash this like 3 times), whip the remaining 1 cup of heavy cream until soft peaks form. Gently fold the whipped cream into the cooled chocolate. If it’s too thin, refrigerate it for a bit until it’s spreadable. Refrigerate until you are ready to use.

This was my favorite part of the whole recipe so don’t skip it!

White Chocolate Glaze

14 ounces white chocolate, coarsely chopped
½ cup heavy cream

DIRECTIONS:
Melt the white chocolate with the heavy cream in a double boiler. Stir the mixture gently with a spatula until smooth. Let cool for 10 minutes and then pour over the chilled opera cake. Using a long cake cake spatula/frosting spreader, smooth the glaze into an even layer. Place the cake into the refrigerator for 30 minutes to set.

ASSEMBLY:

Cut your joconde into four layers. In order to do this, I placed a piece of wax paper over the joconde layer. I measured the width of the cake with a ruler and marked the half way point. I took this measurement and marked it on the halfway point on the length side. I drew lines outlining my 2 rectangular and 2 square pieces and then cut them. Place one square of cake on your cake plate and moisten it gently with the flavoured syrup. Spread buttercream frosting over this layer. Top with the two rectangular pieces of cake, placing them side by side to form a square. Also Moisten these pieces with the flavoured syrup. Spread more buttercream frosting on this layer and then top with the third square of joconde. Use the remaining syrup to wet the joconde and then refrigerate until very firm (at least half an hour). Do not add buttercream to this layer- this is where the mousse will go.

Spread the mousse over the top layer once the cake is firm. Refrigerate for at least two to three hours so the mousse will set.

Make the glaze right before you finish the cake. After the glaze has cooled, pour/spread it over the top of the chilled cake. Refrigerate the cake again to set the glaze.