Preheat your oven to 425°F (220°C) and prepare four ramekins by greasing them with butter and dusting with cocoa powder. This will ensure that your cakes come out easily.
Melt the butter and chocolate together in a microwave-safe bowl or using a double boiler. If using a microwave, heat in short bursts and stir until smooth. Allow to cool slightly.
In a mixing bowl, whisk together the eggs, egg yolks, and granulated sugar until pale and frothy.
Stir in the melted chocolate mixture into the egg mixture. Add in the vanilla extract, flour, and a pinch of salt. Mix until just combined, but avoid overmixing.
Divide the batter evenly among the prepared ramekins, filling them about ¾ full.
Bake in the preheated oven for 12-14 minutes, or until the edges are firm, but the center is still soft.
Let them cool for 1 minute before inverting onto plates. Serve immediately to enjoy the gooey center!
