1. Preheat oven to 425°F (220°C). Generously grease and flour 4 (6-ounce) ramekins. Tap out any excess flour.

2. In a double boiler or a microwave-safe bowl, melt the chopped chocolate and butter together until smooth. Stir frequently. Let the mixture cool for 5-10 minutes.

3. In a medium bowl, use an electric mixer to beat the eggs, egg yolks, and powdered sugar on high speed until pale and thick, about 3-4 minutes.

4. Pour the lukewarm chocolate-butter mixture into the egg mixture and beat on low speed until just combined.

5. Add the flour and salt, and mix on low speed until just incorporated. Do not overmix.

6. Divide the batter evenly among the 4 prepared ramekins.

7. Place the ramekins on a baking sheet. Bake for 12-14 minutes. The edges will be firm, but the centers will be soft and jiggly.

8. Remove from the oven and let the ramekins sit for exactly 1 minute.

9. Place a dessert plate upside down over each ramekin. Carefully and quickly invert the plate and ramekin. Let it sit for 10-15 seconds, then gently lift the ramekin.

10. Garnish with powdered sugar and serve immediately.