Preheat your oven to 425°F (220°C). Butter four ramekins thoroughly and dust insides with flour or finely ground pistachios.

In a double boiler or microwave-safe bowl, melt the unsalted butter, white chocolate, and pistachio paste until smooth (about 1-2 minutes in the microwave, stirring every 30 seconds).

Whisk together the eggs, egg yolks, granulated sugar, and vanilla extract in a large mixing bowl until pale and thick (about 2-3 minutes).

Pour the warm melted mixture into the egg mixture, stirring gently to combine.

Sift and fold in the all-purpose flour and salt until just combined.

Distribute the batter evenly into the prepared ramekins, filling each about three-quarters full.

Bake the filled ramekins in the preheated oven for 11-13 minutes until the edges are set but the centers are slightly jiggly.

Let the ramekins cool for about 1 minute, then run a knife around the edges and invert onto plates. Garnish with chopped pistachios and powdered sugar before serving.