Prep the oven and ramekins: Preheat your oven to 400°F (200°C). Grease two 6-ounce ramekins with butter and dust lightly with cocoa powder. This helps the cakes release cleanly.

Melt chocolate and butter: In a heatproof bowl, melt the butter and chocolate together. Use a microwave in 20–30 second bursts, stirring between, or set the bowl over a pot of simmering water. Stir until smooth and glossy.

Whisk eggs and sweetener: In a separate bowl, whisk the egg, egg yolk, and sweetener until slightly thickened and lighter in color, about 30–45 seconds. This adds volume and helps the center stay molten.

Combine wet ingredients: Slowly pour the warm chocolate mixture into the egg mixture, whisking constantly. Add vanilla, salt, and espresso if using. The batter should be silky and uniform.

Add dry ingredients: Sift in almond flour and cocoa powder. Whisk just until no dry spots remain. Don’t overmix.

Fill ramekins: Divide the batter evenly between the prepared ramekins. Tap gently on the counter to release air bubbles.

Bake: Place on a baking sheet and bake for 8–10 minutes. The edges should look set and slightly puffed, while the center should still jiggle. For a thicker ramekin or cooler batter, add 1–2 minutes.

Rest briefly: Let the cakes sit for 60–90 seconds. This helps the edges firm up just enough for unmolding while keeping the center molten.

Unmold: Run a thin knife around the edge. Invert onto plates and lift off the ramekins. Dust with sugar-free powdered sweetener, add berries or whipped cream, and finish with a pinch of flaky sea salt if you like.

Serve immediately: Lava cakes wait for no one. Enjoy while warm and gooey.