In a medium saucepan on medium heat, whisk together:

   - 4 oz semi-sweet chocolate (chips or chopped)

   - 3/4 cup sugar

   - 1/2 cup heavy cream

   - 1/4 corn syrup

   - 3 Tbs unsweetened cocoa powder

   - 1/8 tsp salt

Whisk continually until the chocolate melts, then allow the mixture to come to a boil, continuing to whisk occasionally. Boil until it reaches 220° (about 3 minutes).

Remove from heat and stir in:

   - 2 Tbs butter (room temperature)

   - 1 tsp vanilla