Butter two 6-ounce ramekins or oven-safe mugs and place on a baking sheet. Set aside.
Ina medium bowl add in the butter and chocolate and gently melt either in the microwave or over a ban-Marie.
Once melted, whisk in the sugar, eggs, vanilla, and coffee until well combined.
Stir in the flour and salt and mix until just combined. Evenly divide the batter between the two prepared dishes.
Bake for 20-22 minutes, or just until there is a jiggle in the center and the edges are set. A soft center ensures lovely lava on the inside.
Remove from the oven and allow to stand for 1 minute before carefully turning out each cake onto your serving dish. Enjoy immediately topped with some vanilla ice-cream.