Preheat your oven to 425°F (220°C).

Generously grease four ramekins with butter.

Melt the butter and chocolate chips together in a microwave-safe bowl, heating in 30-second increments, stirring in between until smooth and glossy.

In a separate bowl, whisk together the eggs, egg yolks, and granulated sugar until frothy.

Gradually add the melted chocolate mixture, stirring gently to incorporate.

Sift in the flour and salt, folding until no dry streaks remain.

Divide the batter evenly among the greased ramekins, filling them about halfway.

Drop a handful of mini marshmallows into each ramekin, then cover them with the remaining batter.

Place the ramekins on a baking sheet and bake for 12-14 minutes.

Let them cool for a minute before inverting onto plates.

Optional: sprinkle more mini marshmallows on top and use a kitchen torch or broiler to toast them for a minute or two.