Source: The New York Times
Yield: 2 1/2 cups
12 oz raspberries, fresh or frozen and defrosted
3/4 c Dutch processed cocoa
3/4 c heavy cream
4 T unsalted butter, at room temperature
1 1/2 c sugar
1/3 c light corn syrup
Puree the raspberries in a food processor and pass them through a fine strainer or food mill to remove seeds. Set aside.
In a medium-sized heavy saucepan, gradually whisk the cocoa into the cream, stirring until smooth. Add the butter, sugar, corn syrup, and raspberries and stir until well blended. Place the pan over medium heat and slowly bring the mixture to a boil, stirring often. Lower the heat to medium-low and let the mixture continue to boil slowly for 8 minutes without stirring. Remove the pan from heat and allow it to cool for 15 minutes if serving hot. Poor sauce into a container, let cool, cover and refrigerate until needed. It will last for at least month. It may be reheated slowly on the stovetop or in a microwave.
Note: I have found that the cocoa doesn't completely dissolve in this sauce which is purely an aesthetic issue. It bothers me a little so I use a stick blender to more completely whisk the ingredients together before heating.