Preheat oven to 425°F (220°C). Generously grease four 6-ounce ceramic ramekins with softened butter, then dust the inside with cocoa powder, tapping out any excess. Place ramekins on a sturdy baking sheet.

In a heatproof bowl set over a pot of barely simmering water (double boiler) or in 30-second microwave bursts, melt the chopped dark chocolate and butter together until silky smooth. Remove from heat and let cool for 3 minutes.

In a medium mixing bowl, whisk together whole eggs, egg yolks, powdered sugar, and pure vanilla extract until pale, slightly frothy, and smooth.

Pour the warm melted chocolate-butter mixture into the whisked eggs, stirring gently with a silicone spatula until thoroughly incorporated and glossy.

Add the flour and sea salt. Fold gently just until no dry flour streaks remain. Divide the rich chocolate batter evenly among the four prepared ramekins.

Bake at 425°F (220°C) for exactly 12-14 minutes. The edges should look firm and cake-like while the center top remains soft and slightly jiggly.

Remove from the oven and let cool undisturbed in the ramekins for 1 minute. Run a small offset spatula or thin butter knife gently around the edges to loosen.

Place an inverted dessert plate over each ramekin and carefully invert together. Let sit for 10 seconds, then lift the ramekin off slowly. Dust with powdered sugar, top with vanilla ice cream and fresh raspberries, and serve immediately while warm.