Whisk the heavy cream until it forms stiff peaks and set in the fridge.

Separate the egg to egg yolk and egg white.

In a small bowl, whisk the egg yolk and sugar for 2 to 3 minutes or until it becomes thick and pale in color and the sugar dissolves, set aside.

In a small saucepan, add about 1 inch of water and bring it to a simmer.

Place a small bowl over the saucepan, add the chocolate, butter, espresso powder, and water over low heat.

Cook everything by constantly stiring until the chocolate melts.

Spoon 1/4 of the chocolate into the egg yolk mixture and mix enough to combine.

Pour the egg yolk mixture back into the chocolate mixture and mix for 5 seconds.

Place the chocolate mixture over the saucepan with simmering water and add the vanilla extract.

By stiring constantly, cook over low heat for 2 ro 3 minutes or until the mixture thickens.

Take off the heat and let it cool for few minutes while stiring frequently.

In a bowl, whisk the egg white until it forms stiff peaks.

Fold the egg white in the cooled chocolate mixture.

Fold the chocolate mixture into the heavy cream but do not over mix.

Pour the chocolate mixture into 4 cups.

Cover the cups with plastic wrap and refrigerate for 4 to 6 hours or overnight.

Add any decorations and they are ready to serve.