Melt the butter and chocolate over low heat in a sauce pan. Set aside. Combine sugar and cornstarch in a mixing bowl. In a separate bowl, whisk the eggs and yolks together. Add the butter-chocolate mixture to the sugar mixture and mix thoroughly. Stir in the eggs and whisk until just smooth. Refrigerate overnight for best results.
Preheat oven to 400 F. Line metal ring molds (about 2 3/4" across by 2" high) with parchment paper. Line baking sheet with parchment paper, place the molds on the baking sheet. Can also use 6oz souffle cups (butter and sugar insides) Scoop the mixture into the molds so they are 2/3 full.
Bake on top rack for 20 minutes. Plate with spatula and then remove ring and parchment. Can be served as is or with Creme Anglais.