Preheat your oven to 425°F (220°C) and grease four ramekins.
Melt the butter and chocolate chips together in a double boiler or microwave.
In a bowl, whisk eggs, egg yolks, and sugar until frothy.
Stir in the melted chocolate mixture and vanilla extract.
Gently fold in the flour and salt until just combined.
Pour the batter evenly into the prepared ramekins.
Bake for 12 minutes until the edges are firm but the center is soft.
Let the cakes cool for 1 minute before inverting onto plates.
Serve immediately, optionally with ice cream or berries.
Enjoy your deliciously gooey lava cake!