Preheat your oven to 425°F (218°C). Generously butter four 6-ounce ramekins and dust them thoroughly with cocoa powder to ensure an easy release.
Melt the dark chocolate and cubed butter together in a double boiler over simmering water until completely smooth. Remove from heat and let cool slightly.
In a large bowl, whisk the whole eggs, egg yolks, vanilla extract, and powdered sugar until pale and slightly thickened.
Gently fold the melted chocolate mixture into the egg mixture using a silicone spatula until well combined.
Sprinkle the premium gluten free baking flour, almond flour, and kosher salt over the batter. Fold gently until just incorporated. Do not overmix.
Divide the batter evenly among the prepared ramekins. Bake for 12 to 14 minutes until the edges are firm but the centers still jiggle slightly.
Let the cakes rest in the ramekins for 1 minute before carefully inverting them onto serving plates. Serve immediately.
