Preheat the oven to 200°C (390°F). Generously butter four 6-ounce (180 ml) ramekins with about 15 g total butter, then dust them with 1 tablespoon cocoa powder, tapping out excess. Place the ramekins on a baking sheet for easy handling.

Melt chocolate and butter

Chop 200 g Valrhona chocolate into small pieces. Place chocolate and 175 g unsalted butter in a heatproof bowl set over (but not touching) simmering water (double boiler) or melt gently in 15–20 second bursts in the microwave, stirring until smooth. If using espresso powder, stir it into the melted chocolate to dissolve. Remove from heat and let cool slightly for 3–4 minutes.

Whisk eggs and sugar

In a separate large bowl, whisk together 4 whole eggs, 2 additional egg yolks, and 150 g granulated sugar until the mixture is pale, slightly thickened and ribbons form when the whisk is lifted (about 2–3 minutes by hand or 1–2 minutes with an electric mixer on medium).

Combine chocolate with egg mixture

Pour the slightly cooled melted chocolate-butter mixture into the egg-sugar mixture in a steady stream, whisking constantly to combine. Continue until homogeneous and glossy.

Fold in dry ingredients

Sift together 60 g all-purpose flour, 15 g unsweetened cocoa powder and a pinch of salt. Fold the dry ingredients gently into the chocolate-egg mixture using a spatula just until incorporated — do not overmix. The batter should be smooth and thick but pourable.

Portion batter and bake

Divide the batter evenly among the prepared ramekins (about 160–170 g batter per ramekin for four). Place the baking sheet with ramekins in the center of the preheated oven. Bake at 200°C (390°F) for 11–13 minutes for a molten center with set edges. If you prefer a slightly firmer center, add 1–2 minutes. Note: ovens vary; watch for risen edges and a slightly domed top with the center visibly softer.

Rest and unmold

Remove ramekins from oven and let rest for 1 minute. Run a small knife around the interior edge of each ramekin to loosen the cake. Invert each ramekin onto a dessert plate and tap or shake gently to release the cake. If cakes stick, let them rest an additional 30 seconds before inverting.

Serve

Place one warm cake on each plate and serve immediately with a scoop (approximately 125 ml) of vanilla ice cream alongside. Optionally dust with a little powdered sugar or extra cocoa, or garnish with fresh berries or a sprig of mint.

Vanilla Ice Cream (quick assembly for serving)

Scoop vanilla ice cream into four portions (about 125 ml per portion). If using vanilla bean paste or extract, briefly fold it into softened ice cream, then refreeze for 10–15 minutes to firm slightly before serving alongside the warm cakes. Keep ice cream in the coldest part of the freezer until plating.