Preheat your oven to 425°F (220°C) for a perfect molten center.
Grease each ramekin with unsalted butter and dust with flour.
In a microwave-safe bowl, combine butter and chocolate chips. Heat in 30-second intervals until melted and smooth.
In a mixing bowl, whisk together eggs, yolks, sugar, salt, and vanilla until combined. Gradually add melted chocolate, stirring continuously.
Gently fold in flour until just combined; do not overmix.
Evenly distribute the batter among the prepared ramekins, filling each about 3/4 full.
Place ramekins on a baking tray and bake for 12-14 minutes, or until edges are set but the center is still soft.
Remove from oven, cool for a minute, run a knife around edges, and invert onto a plate. Serve immediately.
