Combine all ingredients, except the pears and raspberry filling, in a non-reactive saucepan and bring to a boil over high heat. Reduce the heat to a gentle simmer and add the pears. Add enough cold water to cover pears and simmer for 15 to 20 minutes. Once thickened, remove pears and chill.
Add raspberry filling to port syrup and bring to a boil. Cook until reduced to the consistency of a glaze. Remove from heat and let cool to room temperature. Spoon pears into bowls and top with glaze. Garnish with whipped topping and fresh mint, if desired.