French
Opéra Cake
Razor-thin joconde, coffee syrup, French buttercream, ganache, and dark glaze form an exacting stack of bittersweet, satin layers.
16 servings · 140 minutes prep · 25 minutes cook
Ingredients
Joconde
- 1 1/2 cups almond flour
- 1 1/4 cups confectioners’ sugar
- 4 large eggs
- 1/3 cup cake flour
- 4 egg whites
- 2 tbsp sugar
- 2 tbsp melted butter
Coffee buttercream and syrup
- 2/3 cup strong espresso, 1/2 cup / 120 ml for syrup; 2 tbsp / 30 ml for buttercream; remainder allows for loss
- 1 1/4 cups sugar, divided
- 4 egg yolks
- 12 tbsp cool pliable butter
- 1/4 cup water, for the buttercream sugar syrup
Ganache and glaze
- 14 oz dark chocolate, divided
- 3/4 cup heavy cream
- 3 tbsp butter
- 2 tbsp neutral oil
Directions
Bake joconde
- Heat the oven to {{temperature:425F}}. Whip almond flour, powdered sugar, eggs, and cake flour until thick and ribboning. Whip egg whites with sugar to medium peaks; fold in, then fold in butter. Spread evenly in a parchment-lined 13-by-18-inch rimmed baking sheet and bake until springy and barely golden, 7-9 minutes.
Prepare fillings
- Warm 1/2 cup espresso with 1/2 cup sugar only until dissolved, then simmer 1 minute and cool. Cook the remaining sugar with water to {{temperature:240F}}, stream it into whipping egg yolks, and beat until the bowl is cool. Beat in butter gradually, then add 2 tbsp espresso a teaspoon at a time, stopping if the emulsion begins to loosen.
- Pour hot heavy cream over half dark chocolate, stir smooth, then add butter.
Layer and glaze
- From the cooled 13-by-18-inch joconde, cut three exact 6-by-10-inch rectangles. Set the first on a flat parchment-lined board, brush it lightly with coffee syrup, and spread half the coffee buttercream precisely to its edges; add the second, brush with syrup, and spread all the ganache; add the third, brush with syrup, and spread the remaining buttercream. Use the sponge edges as the alignment guide and chill each soft layer briefly before adding the next so the free-standing rectangle remains level.
- Melt remaining chocolate with neutral oil, cool to fluid body temperature, glaze the cold cake, chill, then trim all edges and cut with a hot dry knife.
