Grease ramekins with butter and dust with cocoa powder. This helps cakes release easily after baking and keeps edges smooth and neat.

Place chocolate and butter in a bowl. Melt using double boiler or microwave. Stir until smooth and shiny without lumps for best texture.

In another bowl, whisk eggs, egg yolks, and sugar. Beat until light and slightly thick. This step creates soft and airy cake texture.

Slowly pour melted chocolate into egg mixture. Stir gently to combine. Add vanilla extract and salt for extra flavor balance.

Add flour into mixture and fold gently. Do not overmix. Batter should stay smooth and slightly thick for perfect lava center.

Divide batter evenly into prepared ramekins. Place them on a baking tray. Leave a little space at top for rising during baking.

Preheat oven to 425°F. Bake for about 10 to 12 minutes. Edges should be firm, but center should stay soft and slightly jiggly.

Let cakes rest for one minute. Carefully invert onto plates or serve in ramekins. Cut gently and watch the warm chocolate flow out.