Melt the chocolate and margarine in a double boiler (or in a bowl over boiling water). When completely melted, whisk in the sugar and prunes.
In a separate bowl, combine the flour and baking powder. Pour the chocolate mixture into the flour mixture and gently fold them together until combined. Stir in the vanilla.
Line a 9X9 pan with parchment paper. Pour the batter into the pan. Bake at 350 degrees for 35-40 minutes until they look set. Let cool in pan.
Once cool, cut into squares. For additional fanciness, dust the tops with cocoa powder or powdered sugar.
These freeze really well.
Kay: They are really good!
Mom (Dana): My dad hates prunes so I new these were a hit when he kept talking about how good they were!