1. MAKE THE PISTACHIO LAVA CENTERS: Warm the heavy cream in a small saucepan over low heat until steaming. Pour over the white chocolate chips in a heatproof bowl and let sit 1 minute. Stir until mostly melted, then mix in the finely ground pistachios and a pinch of salt. Blend briefly if needed for a silky texture. Cool to room temperature, then spoon marble sized rounds onto a parchment lined tray. Freeze at least 1 hour until fully solid.

2. PREPARE THE CHOCOLATE BATTER: Melt the dark chocolate and butter together in a heatproof bowl using a double boiler or the microwave in 30 second bursts, stirring until smooth and glossy. In a separate bowl whisk the whole eggs, egg yolks, sugar, and a pinch of salt until pale and thick. Gently fold the melted chocolate into the egg mixture. Sift in the flour and fold just until combined into a smooth, slightly thick batter.

3. ASSEMBLE THE CAKES: Grease six ramekins thoroughly. Spoon about 1 tablespoon of batter into each. Nestle one frozen pistachio ball in the center of each, not touching the sides. Cover with more batter until each ramekin is about 3/4 full. Optionally press a small piece of dark chocolate on top.

4. BAKE: Preheat the oven to 425°F, 220°C. Place ramekins on a baking sheet and bake 10 to 12 minutes. Edges should be set and the centers should jiggle slightly when gently shaken. Rest 1 to 2 minutes. Run a thin knife around edges and invert onto plates, or serve directly in the ramekins.

5. SERVE: Dust with powdered sugar, sprinkle with crushed pistachios, and serve immediately with fresh berries or a scoop of vanilla or pistachio ice cream. Enjoy the molten pistachio center while warm.