Prep your ramekins. Grease 4 small ramekins (about 6 ounces each) well with butter. You can also dust them with a little cocoa powder to prevent sticking and add flavor.

Preheat the oven. Set to 400°F (200°C). A hot oven is key to getting set edges and a soft, molten center.

Melt the butter and chocolate. In a heatproof bowl, gently melt 6 tablespoons butter with 3 ounces sugar-free dark chocolate. Use a microwave in 20-second bursts or a double boiler. Stir until smooth and glossy.

Mix dry ingredients. In a small bowl, whisk 1/3 cup super-fine almond flour, 3 tablespoons unsweetened cocoa powder, 1/4 cup granulated erythritol or allulose, and a pinch of salt. If using espresso powder, add 1/2 teaspoon here.

Whisk eggs and vanilla. In a separate bowl, beat 2 large eggs with 1 teaspoon vanilla until slightly frothy. This helps with lift and a light edge.

Combine the batter. Stir the melted chocolate mixture into the eggs while whisking. Add the dry ingredients and fold gently until just combined. The batter will be thick and glossy.

Fill the ramekins. Divide the batter evenly among the prepared ramekins. For extra lava, press a small square of sugar-free chocolate into the center of each and cover with a little batter.

Bake. Place ramekins on a baking sheet and bake for 9–11 minutes. The tops should look set and puffed, but the centers should still feel soft when touched. Err on the side of slightly underbaked.

Rest briefly, then unmold. Let sit 1–2 minutes to settle. Run a thin knife around the edge, then invert onto small plates. If you prefer, you can serve straight from the ramekins with a spoon.

Garnish and serve warm. Add sugar-free whipped cream, a few berries, or a light dusting of powdered sweetener. Serve immediately for the best molten texture.