Opera cake is a relatively new (1950s), yet classic, French pastry known for its thin layers of many components — three layers of almond sponge cake soaked in espresso syrup, espresso buttercream, ganache, and a dark chocolate icing or glaze. We’re keeping with the traditional square shape and trimmed, unfrosted sides. Traditionally it’s decorated with the name “Opera” written on top, accompanied by some gold leaf. We’re simplifying things with a no-fuss gold luster dust embellishment.
But, let’s break down each component. The sponge cakes are light and tender, getting their ethereal texture (and leavening) from beaten egg whites. Brushing each layer with a flavored simple syrup helps keep the cakes moist and adds some sweetness and flavor. The creamy Swiss Coffee Buttercream isn’t your usual powdered sugar frosting. And unlike many Swiss meringues, this one cooks the eggs to 160 degrees, so you know it’s safe to eat, plus it gives extra stability to the meringue. The ganache is rich and creamy and does double-duty as the glaze. But best of all, each element can be made ahead, making this an approachable celebratory dessert. If you’re a fan of coffee and chocolate, this beauty is for you. It’s rich yet not filling and truly is a pièce de résistance.
FOR THE COFFEE SWISS BUTTERCREAM:
FOR THE ESPRESSO SYRUP:
FOR THE DARK CHOCOLATE GANACHE:
How to Make Ahead
You can make the cake layers ahead. After cooling, wrap them tightly in plastic wrap, then foil, and place in a large resealable plastic bag. Leave them at room temperature for 3–5 days, or freeze for longer storage.
Preheat oven to 425°. Coat three 8-inch square baking pans with butter, line with parchment, and coat paper with butter. Dust pans with flour and shake out excess.
Beat almond flour, powdered sugar, whole eggs, butter, and salt with a hand mixer on medium-high speed until light and combined, 2–3 minutes. Add all-purpose flour; beat on low speed just until combined.
Whisk egg whites and cream of tartar with a hand mixer on medium speed until soft peaks form; increase speed to medium-high. Gradually sprinkle in 2 Tbsp. granulated sugar and beat until whites are stiff and glossy, but not dry, 1 minute more.
Whisk one-fourth of whites into almond flour mixture until combined. Fold in remaining whites, in three additions, adding more when no streaks remain. Divide batter evenly among prepared pans.
Arrange one cake on a serving plate. Brush cake with one-third syrup then spread half the buttercream on top; top with another cake. Brush second cake with one-third syrup and top with three-fourths ganache; top with remaining cake. Brush third cake with remaining one-third syrup and top with remaining buttercream. Chill cake at least 1 hour.
Heat remaining one-fourth ganache in microwave on high until shiny and pourable, but not hot, 20 seconds; pour remaining ganache on top of buttercream and smooth. Chill cake until ganache sets, about 1 hour; trim edges of cake.
Sprinkle top of cake with luster dust.
For the Coffee Swiss Buttercream
Whisk together espresso powder, water, and vanilla until espresso powder dissolves.
Heat egg whites, sugar, and salt in the bowl of a stand mixer over a pan of simmering water, whisking often (do not let the bottom of the bowl touch the water) until sugar dissolves, mixture thickens, and registers 160°, 5–10 minutes.
Off heat, beat egg white mixture in a stand mixer fitted with the whisk attachment on medium-high speed until whites are stiff, glossy, and tripled in volume, 5–10 minutes, then cool to 80–90° (if not there already).
Add butter, one piece at a time, beating until incorporated before adding the next. (If frosting doesn’t stiffen, chill it in the refrigerator for 20 minutes, then resume beating.)
Beat in espresso mixture until combined. (Frosting can be made and stored in an airtight container in the refrigerator up to one week ahead; bring to room temperature and rewhip before using.)
For the Espresso Syrup
Heat water, sugar, espresso powder, and salt in a saucepan over medium-high until beginning to boil and sugar dissolves. Reduce heat to low; simmer syrup for 5 minutes. Let syrup cool to room temperature. (Syrup can be made and stored, covered, in the refrigerator up to 1 week ahead.)
For the Dark Chocolate Ganache
Heat heavy cream and corn syrup in a saucepan over medium to a simmer.
Off heat, stir in chocolate and butter; let stand 10 minutes, then whisk until smooth. Stir in vanilla.
% Daily Value*
Total Fat 30g 46%
Saturated Fat 15g 75%
Cholesterol 119mg 39%
Sodium 107mg 4%
Carbs 45g 15%
*Percent Daily Values are based on a 2,000 calorie diet.