Instructions

1. Preheat the oven to 425, and spray 2 6-ounce ramekins very well with cooking spray.
2. In a small bowl, combine the chocolate chips and butter. Heat in 15-second pulses in the microwave, stirring in between each pulse until the chocolate is almost melted. Remove it from the microwave before the chips melt all the way, and stir to melt them entirely. The mixture should be smooth and shiny.
3. In a medium bowl, beat together with an electric mixer on medium-high speed the egg, egg yolk and sugar. Beat until light and fluffy--it will fall off the beaters in ribbons.
4. Next, add the salt, espresso powder and vanilla extract. Beat until just combined.
5. Stream in the melted chocolate and butter, and beat until combined.
6. Finally, fold in the flour with a spatula.
7. Divide the mixture between the two ramekins. Place the ramekins on a small baking sheet.
8. Bake for 13-14 minutes, until the tops of the cakes appear dry and the edges are starting to turn dark brown.
9. Let the cakes rest for 1 minute only on the baking sheet. If you let them sit longer, they will finish cooking al the way through.
10. Run a knife around the edges of each ramekin, and tip the cake out onto the plate.
11. Serve immediately.