Preheat your oven to 425°F (220°C) and grease six ramekins with unsalted butter, dusting with all-purpose flour.

Melt the unsalted butter and semi-sweet chocolate in a saucepan over low heat, stirring until smooth, about 5 minutes.

Add granulated sugar to the melted chocolate mixture and whisk until combined and smooth, about 1-2 minutes.

Gradually whisk in the eggs and yolks one at a time, ensuring the mixture is smooth and glossy after each addition.

Stir in vanilla extract and salt, mixing well to maintain the batter's consistency.

Fold in all-purpose flour and chopped pistachios carefully to combine without overmixing.

Divide the batter evenly among the prepared ramekins, filling each about three-quarters full.

Bake in the oven for 12-14 minutes until the edges are firm and the center is soft.

Let them cool for 3-5 minutes, then run a knife around edges and invert onto plates.

Serve warm with optional vanilla ice cream or whipped cream and enjoy!