Steps
1. Preheat the oven to 425°F (220°C) and grease a ramekin with butter.
2. In a microwave-safe bowl, melt the chocolate chips and butter together in 30-second intervals until smooth. Let it cool slightly.
3. In a separate bowl, whisk the egg and sugar until well combined. Stir in the melted chocolate mixture.
4. Fold in the flour and salt until just combined.
5. Pour the batter into the prepared ramekin and bake for 12-14 minutes, or until the edges are set but the center is still soft.
6. Let it cool for a minute, then run a knife around the edges and invert the cake onto a plate.
7. Serve warm with a scoop of vanilla ice cream, if desired.