Preheat your oven to 425°F (220°C). Grease four ramekins generously with butter and sprinkle a bit of flour inside, shaking out the excess.

In a microwave-safe bowl, combine the butter and semisweet chocolate chips. Heat in 30-second intervals, stirring in between, until they are completely melted and smooth.

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

Gradually pour the melted chocolate mixture into the egg mixture, stirring well. Gently fold in the all-purpose flour and salt until everything is combined.

Divide the batter equally among the prepared ramekins, filling them about 3/4 of the way full.

Place the ramekins on a baking tray and bake for 10 to 12 minutes, or until the edges are firm but the center remains soft.

Remove from the oven and let cool for 1 minute. Carefully invert each ramekin onto a plate and dust with powdered sugar. Serve immediately.