Preheat your oven to 425°F (220°C). Brush the insides of four 4-ounce ramekins generously with melted butter, then dust with cocoa powder, tapping out the excess. Place them on a baking sheet.

In a heatproof bowl set over a saucepan of simmering water (double boiler), combine the chopped chocolate and butter. Stir gently until completely melted and smooth. Remove from heat and let cool slightly for 3–4 minutes.

In a separate mixing bowl, whisk together the eggs, egg yolks, sugar, and salt until the mixture is pale, thick, and ribbony—about 2–3 minutes by hand or 1 minute with an electric mixer.

Pour the slightly cooled chocolate mixture into the egg mixture and fold gently with a rubber spatula until just combined. Sift the flour over the top and fold again until no streaks remain. Do not overmix.

Divide the batter evenly among the prepared ramekins (about 1/2 cup each). Bake for 12–14 minutes, until the edges are set and the center jiggles slightly when shaken. The top should look dry and cracked. For food safety, note that the center will be molten and undercooked; to reduce risk, use pasteurized eggs or ensure the entire cake reaches 160°F (71°C).

Remove from the oven and let the cakes rest in the ramekins for exactly 30 seconds. Run a thin knife around the edges, place a serving plate upside down on top, and carefully invert. Gently lift off the ramekin.

Dust with powdered sugar, add a few raspberries on the side, and serve immediately while the center is still molten.