Preheat oven to 350 degrees F (175 degrees C). Oil a 9x13-inch baking dish with canola oil.
Bring a large pot of water to a boil, and stir in the baby carrots. Reduce heat to a simmer, and cook the baby carrots until firm but tender, about 10 minutes. Stir in the sweet potato chunks, and simmer for 5 more minutes; drain.
Place the carrots, sweet potatoes, and prunes into the prepared baking dish, and stir to combine. In a bowl, whisk together the reserved pineapple juice, honey, orange juice, salt, and cinnamon until smooth, and pour the mixture over the carrots, sweet potatoes, and prunes. Cover the baking dish with aluminum foil.
Bake in the preheated oven until the mixture is bubbling, about 30 minutes. Remove from oven, and take off the aluminum foil. Mix in the pineapple chunks and cornstarch until thoroughly combined, and return to the oven until slightly thickened, about 10 more minutes.
