For the light version: Preheat oven to 350 °F.
Place a generous layer of leftover veggies in a casserole dish and cover them with the chicken stock, salt, ground black pepper and Parmigiano Reggiano.
Cover dish with a piece of parchment paper and bake until the veggies are tender. Remove the parchment paper and continue baking until the cheese browns.
For the rich version: Preheat oven to 350 °F.
Place a generous layer of leftover veggies in a casserole dish and cover them with heavy cream, salt, ground black pepper and cheese. Cover dish with a piece of parchment paper and bake until the veggies are tender and the cheese has melted.