Preheat oven to 350F.

Coat a pound cake mold with melted butter and sprinkle with granulated sugar.

Sift the cornstarch and cocoa powder into a medium bowl and set aside until use.

Add the butter and chopped dark chocolate into a large bowl and melt them in warm water on the stove(50C).

In a medium bowl, whisk together the eggs and sugar until smooth. Add the egg mixture to the chocolate mixture and stir until well mixed. Add the dry mixture to the chocolate mixture and stir until smooth. Strain the mixture and pour it into the mold.

Place a cookie sheet on the middle oven rack. Set the cake mold on the cookie sheet. Fill the cookie sheet with boiling water.

Bake until the dough doesn't stick to your finger when touched, about 60 minutes (be careful not to bake too long). Let cool completely. Remove the terrine and freeze until use.

Store the terrine at room temperature for 1 hour or in your fridge for 3 hours before serving.

More Details at http://www.chez-k.org/english/chocolates/chocolate-terrine/