Classic Opéra Cake with Espresso Buttercream and Mirror Chocolate Glaze

⏱ 240 min · Serves 12

Six whisper-thin layers of almond joconde soaked in espresso syrup, sandwiched with silky coffee buttercream and dark chocolate ganache, then sealed under a glossy chocolate glaze. It's a weekend project that eats like a Parisian patisserie window — cut it into neat little rectangles and watch the room go quiet.

Per serving: 642 kcal · 9.5g protein · 48.0g carbs · 46.0g fat

Ingredients

• FOR THE JOCONDE SPONGE:
• 150g ground almonds
• 150g icing sugar
• 4 large eggs
• 40g plain flour
• 4 large egg whites
• 30g caster sugar
• 30g unsalted butter, melted and cooled
• FOR THE ESPRESSO SYRUP:
• 100g caster sugar
• 100ml water
• 2 tbsp instant espresso powder (or 60ml strong espresso)
• FOR THE COFFEE BUTTERCREAM:
• 2 large eggs
• 120g caster sugar
• 40ml water
• 250g unsalted butter, soft but cool, cubed
• 2 tbsp instant espresso powder dissolved in 1 tbsp hot water, cooled
• pinch of fine salt
• FOR THE GANACHE:
• 200g dark chocolate (60–70%), finely chopped
• 200ml double cream
• 20g unsalted butter
• FOR THE GLAZE:
• 150g dark chocolate (55–60%), chopped
• 40g flavourless oil (sunflower or grapeseed)
• a few gold leaf flakes or coffee beans, to finish (optional)

Method

1. Heat oven to 210C/190C fan. Line two large baking trays (about 30x40cm) with baking parchment.
2. Whisk ground almonds, icing sugar, whole eggs together for 4–5 minutes until pale and thick, then fold in the flour.
3. In a clean bowl, whisk the egg whites to soft peaks, add the caster sugar and whisk to a glossy medium peak. Fold a third into the almond mixture to loosen, then fold in the rest, followed by the melted butter.
4. Spread the batter evenly and thinly across both trays (about 5mm deep). Bake 7–9 minutes until just set and lightly golden. Cool, then cut each sheet into two equal rectangles — you want 3 matched layers plus a spare (about 20x30cm each, or trim to your preferred size).
5. Espresso syrup: bring sugar and water to the boil, stir in the espresso powder, cool.
6. Buttercream: whisk the eggs in a stand mixer until pale. Meanwhile boil the sugar and water to 118C. With the mixer running, pour the syrup down the side of the bowl in a steady stream. Whisk until the bowl is cool to the touch (8–10 minutes). Add the butter a few cubes at a time, then the coffee and salt. Whisk until silky. If it splits, keep whisking — it will come back.
7. Ganache: heat the cream to a simmer, pour over the chocolate, wait 1 minute, stir smooth, then beat in the butter. Cool to a thick, spreadable consistency.
8. Assemble on a parchment-lined board: layer 1 of joconde, brush generously with syrup, spread half the buttercream. Layer 2, syrup, all the ganache (reserve 3 tbsp). Layer 3, syrup, remaining buttercream, smoothed absolutely flat with an offset palette knife. Chill 1 hour until firm.
9. Glaze: melt the glaze chocolate with the oil until smooth, cool to just warm (30C). Pour over the chilled cake and tilt gently to a thin even coat. Chill 30 minutes.
10. Trim all four edges with a hot, dry knife to reveal the layers. Cut into 12 neat rectangles, wiping the blade between cuts. Finish with gold leaf or a coffee bean and serve at cool room temperature.
11. Tip: the cake is better made a day ahead — the layers settle and the flavour deepens.