Preheat oven to 375 degrees F (190 C). Lightly grease and flour a metal 8-inch round cake pan, then cut a piece of parchment to fit and lay it in the bottom of the pan.

To make the cake, combine chocolate and butter in a large microwave-safe mixing bowl, and heat until the butter is melted and the chips are soft. Stir and continue heating in brief intervals until the chips fully melt and the mixture is smooth.

Stir in the sugar, salt, espresso powder, and vanilla.

Add the eggs, beating mixture briefly until they are fully incorporated and smooth.

Add the cocoa powder, and stir gently just until combined.

Pour batter into the prepared pan, and bake the cake for about 25 minutes; when it is done, the top will have a thin crust, and the cake will register 200 degrees F (94 C) on an instant-read thermometer inserted into the middle.

After removing cake from the oven, let it cool for about 5 minutes in the pan. Then, run a knife around the inside edge, turn the pan upside-down over a serving plate, and shake or tap gently to loosen the cake. Allow to cool completely before adding the glaze.

To make the glaze, combine chocolate and cream in a microwave-safe bowl. Heat until the cream is very hot, but not simmering. Remove from the microwave, and stir until the chocolate melts and the mixture is completely smooth.

Pour glaze over the cake and allow to set for several hours before garnishing and serving.