For the compote, in a large saucepan, combine the boysenberries, sugar to taste, orange juice and nutmeg. Dissolve the cornstarch in the warm water and set aside. Bring the fruit mixture to a boil and remove from heat. Pour about half of the cornstarch liquid into the boysenberry mixture and return the saucepan to the heat. Whisking constantly, bring the compote back to a boil. The compote should be thick enough to coat the back of a spoon. If necessary, add the remaining cornstarch in the same manner as before. Keep warm.