DB May Challenge: Opera Cake

This month's challenge was an Opera Cake, and I chose to make a lavender Opera Cake because of the spring-y flavor. I loved the delicate taste of the cake and the mousse was absolutely amazing! The cake was lots of work, but also delicious, so thanks to Ivonne and Lis for a fabulous challenge this month!

The Opera Cake involves five elements: joconde, buttercream, syrup, mousse, and glaze. I've listed my alterations to the recipe below, but you can see the original recipe here. I made a half-recipe of the cake and baked it in round pans. I also used oat flour instead of almond meal in the joconde. This worked well...I was a little worried when I pulled the cakes out of the oven because they smelled a tad like oatmeal, but once it was all cooled and put together the cake was fantastic.

This month's challenge is dedicated to Barbara for all her work on the Taste of Yellow blog event in support of LiveSTRONG.

1. Lavender Syrup
2 c sugar
1 c water
2 tsp dried lavender flowers

Bring everything to a simmer and stir until the sugar dissolves. Let steep 10-15 minutes off the heat, then strain into a tupperware. Cover and store in the refrigerator until ready to use.

2. Joconde (Cake)

3 egg whites
1 T granulated sugar
1 c icing sugar
2 tsp lavender flowers
1 c oat flour
3 whole eggs
1/4 c all purpose flour
1 1/2 T butter, melted and cooled

Preheat the oven to 425 degrees. Spray 2 9-inch round cake pans with cooking spray.

Beat the egg whites and granulated sugar until they form stiff, glossy peaks. Set aside.

Pulse icing sugar and lavender flours in a food processor for a couple of minutes. Then put them in a bowl with the oat flour and eggs. Beat on medium speed until thick and voluminous (3-4 minutes). Add the all-purpose flour and beat on low speed just for a couple of seconds until everything is combined. Gently fold in the egg whites and then the cooled butter with a rubber spatula.

Pour about one third of the batter into each of the two pans and bake in the oven for about 5-9 minutes until the edges are brown and the cakes are springy. (It will just be a little bit of batter in each pan--the cake layers are very thin.) Once they are cooked, run a knife around the edges, cover the pan with wax paper, and turn out onto a plate. Wash one pan in cold water to cool it off, dry, re-oil, and cook the remaining batter in the same manner. You will end up with three thin layers, all on wax-papered plates.

3. White Chocolate Ganache/Mousse

3.5 oz. good quality white chocolate (I recommend Green & Blacks)
1 1/2 T heavy cream + 1/2 c heavy cream
1/2 T lavender syrup (from Step 1)

Melt the white chocolate and 1 1/2 T cream in a small saucepan. Stir the whole time with a rubber spatula. It will look curdled for a while but will come together. When everything is melted, take off the heat and keep stirring until smooth. Add the lavender syrup and stir to combine. Keep stirring it every couple of minutes until it is cooled (but not hard).

Beat the remaining 1/2 c heavy cream until you get stiff peaks. Put a little bit in the chocolate and stir to lighten the chocolate. Then put the chocolate into the bowl with the whipped cream and gently fold in. Chill until ready to use.

4. Buttercream

1/2 c sugar
2 egg whites
1 1/2 sticks unsalted butter, soft
2 T lavender syrup, above
red and blue food coloring

Whisk the sugar and whites together in the top of a double boiler. Heat until hot to the touch, whisking constantly. Remove from heat and immediate beat with a hand mixer on medium high speed until voluminous, shiny, and cool. Beat in the butter 1/2 stick at a time. Add the lavender syrup 2 tsp at a time until you get the flavor and sweetness you want, and then add 2 drops of red coloring and 2 drops of blue food coloring to make a lavender frosting. Beat until the frosting is smooth and thick.

5. White Chocolate Glaze
(Make this after the rest of the cake is already assembled and chilled.)

7 oz. white chocolate
1/4 c heavy cream

Melt the white chocolate with the heavy cream. Whisk the mixture gently until smooth. Let cool for 10 minutes before pouring over the chilled cake.

Assembly

Ok, so now you have three cake rounds, syrup, buttercream, and mousse (you'll make the glaze after assembling the rest of the cake). Place the first round on your serving platter and moisten with the lavender syrup (I used a pastry brush). You can be pretty liberal with the syrup. Then cover generously with about half the buttercream. Repeat with layer two. Put on the final round of cake, and moisten with the syrup. Cover with the mousse and spread everything out as smoothly as possible. Chill the cake until firm (a couple of hours).

Then, make the glaze and let cool about 10 minutes. Pour carefully over the top of the cake and smooth it out. Refrigerate the cake again until well chilled. Decorate and enjoy! :)