01 - Preheat oven to 425°F. Generously butter 4 individual ramekins and lightly dust with flour, tapping out any excess to ensure clean release.
02 - In a food processor, pulse the pistachios until finely ground. Add the heavy cream and blend until a thick, smooth paste forms. Set aside.
03 - Set a heatproof bowl over a pot of barely simmering water. Add the chopped chocolate and butter, stirring gently until glossy and completely smooth. Remove from heat and let cool slightly.
04 - In a separate bowl, whisk together the eggs, egg yolks, and granulated sugar until the mixture turns pale and falls in thick ribbons.
05 - Pour the melted chocolate mixture into the egg mixture, whisking gently to combine. Sift in the flour and salt, then fold until just incorporated. Do not overmix.
06 - Divide half the batter evenly among the 4 prepared ramekins. Spoon a heaping teaspoon of pistachio paste into the center of each. Cover with the remaining batter, smoothing the tops.
07 - Bake for 11 to 13 minutes, until the tops are set and the edges pull away slightly, but the centers remain soft and jiggly.
08 - Immediately run a knife around the inside edges of each ramekin. Let rest for 1 minute, then invert onto serving plates. Garnish with chopped pistachios, a dusting of powdered sugar, and a scoop of vanilla ice cream if desired. Serve immediately.