In a large saucepan over medium heat, mix together the orange juice, brown and white sugar, vanilla extract, and cinnamon. Bring the mixture to a boil, stirring to dissolve the sugar. Place pears into the syrup, and cover; simmer pears for 1 hour and 15 minutes, spooning sauce over pears every 10 minutes, and turning pears over twice during cooking time.
Transfer pears to individual serving dishes. Continue cooking the syrup, stirring often, until thickened, about 15 more minutes, then mix in the walnuts. Pour the sauce over the pears to serve.
