Prep the oven and ramekins. Preheat your oven to 400°F (200°C). Generously butter two 6-ounce ramekins and dust lightly with cocoa to prevent sticking.

Melt chocolate and butter. In a heatproof bowl, gently melt the dark chocolate and butter together. Use a microwave in 15–20 second bursts or a double boiler. Stir until smooth and glossy, then let it cool for 2 minutes.

Whisk eggs and sweetener. In a separate bowl, whisk the egg, egg yolk, sweetener, vanilla, and salt until slightly thickened and pale, about 30–45 seconds. This helps with structure.

Combine wet ingredients. Slowly drizzle the melted chocolate mixture into the egg mixture while whisking. This prevents scrambling and keeps the batter silky.

Add dry ingredients. Sift in the almond flour and cocoa powder (and espresso powder if using). Fold gently just until no dry streaks remain. The batter should be smooth and pourable, not runny.

Fill the ramekins. Divide the batter evenly between the two ramekins. Tap each ramekin lightly on the counter to release air bubbles.

Bake briefly. Place the ramekins on a small baking sheet and bake for 8–10 minutes. The edges should look set and puffed, but the center should still jiggle slightly. For a thicker lava, aim for 8 minutes; for less lava and more cake, go closer to 10.

Rest and release. Let the cakes sit for 1 minute. Run a thin knife around the edge to loosen. Invert each ramekin onto a plate and lift carefully.

Finish and serve. Top with a few raspberries, a spoonful of whipped cream, or a dusting of cocoa. Serve immediately for maximum molten goodness.