Preheat oven to 425°F (220°C). Grease and lightly flour 4 ramekins (6-ounce size).
In a microwave-safe bowl, melt butter and chocolate together in 30-second intervals, stirring until smooth. Let cool slightly.
In a medium bowl, whisk together eggs, egg yolks, sugar, and vanilla until light and slightly thick.
Stir the melted chocolate mixture into the egg mixture.
Gently fold in flour, salt, and ground pistachios until just combined. Do not overmix.
Divide batter evenly among the prepared ramekins. Place them on a baking sheet.
Bake for 11–13 minutes, until the edges are firm but the center is still soft.
Let cool for 1 minute, then carefully invert onto plates. Dust with powdered sugar, sprinkle with pistachios, and serve warm with ice cream if desired.
Prep Time: 10 minutes | Cook Time: 12 minutes | Total Time: 22 minutes
Kcal: Approx. 400 per cake | Servings: 4