Chocolate Mug Mousse

Place the chopped chocolate in a heatproof bowl. Melt the chocolate over a double boiler or in the microwave in 15-20 second bursts, stirring between each burst to prevent burning, until smooth. Let the chocolate cool slightly without letting it set.

In a small bowl, whisk the egg yolk with the sugar until pale and slightly thickened. In a clean, dry bowl, whip the egg white with a pinch of salt until soft peaks form. Don't over-whip the whites, or the mousse will turn out grainy.

Gently pour the slightly cooled melted chocolate into the whipped yolk and mix until combined.

In a few additions, gently fold the whipped egg white into the chocolate-yolk mixture using a spatula or spoon. Use a bottom-to-top motion to keep the mousse light and airy, and avoid over-mixing.

Transfer the mousse into a nice mug or dessert glass. Chill in the refrigerator for at least 30 minutes to set and firm up, though letting it rest in the fridge for 1-2 hours is even better.