Preheat your oven to 400°F / 200°C. Generously grease three 6-ounce ramekins with butter or coconut oil.
In a double boiler or a heatproof bowl set over a saucepan of simmering water, melt the chopped chocolate and coconut oil together, stirring until smooth.
Remove from heat and let it cool for 5-10 minutes until it's warm, not hot.
In a separate medium bowl, whisk the egg yolks with the Swerve Sweetener until pale and slightly fluffy. Gently whisk this mixture into the cooled chocolate until just combined.
In a clean, dry bowl using an electric mixer, beat the egg whites until they form soft, billowy peaks.
Gently fold about one-third of the beaten egg whites into the chocolate mixture to lighten it.
Then, carefully fold in the remaining egg whites until no white streaks remain, being careful not to overmix.
Divide the batter evenly among the prepared ramekins, filling them no more than two-thirds full.
Place the ramekins on a baking sheet and bake for 7-10 minutes. The edges will look set and may have a few small cracks, but the center should still be soft and jiggly.
Carefully remove from the oven and let the cakes cool in their ramekins for 2-3 minutes. To serve, run a thin knife around the edge of each cake and invert onto a serving plate, or simply enjoy it warm directly from the ramekin.
Do not overbake! The key to the molten 'lava' center is pulling the cakes from the oven when the center is still very soft and jiggly. The cakes will continue to cook slightly as they rest.