How to Make It
In a small saucepan, combine the Devonshire cream and milk and bring to a simmer over moderate heat. In a small bowl, beat the egg. Slowly whisk 1/2 cup of the simmering cream into the beaten egg, then whisk the mixture into the cream in the saucepan. Cook for 30 seconds, whisking constantly.
Put the chocolate in a blender. Pour in the hot cream mixture and let stand for 3 minutes. Blend until smooth, about 30 seconds. Set 6 espresso cups on a baking sheet and fill them with the chocolate cream. Cover and refrigerate until chilled and firm, about 2 hours. Top each chocolate pot with a dollop of Devonshire cream and serve.