Step 1Heat the oven to 425 degrees. Lightly coat a 2 ½- to 3-quart shallow baking dish with oil.
Step 2Heat both oils in a Dutch oven or large saucepot over medium-high heat. Add the onion, celery and a generous pinch of salt and pepper. Cook, stirring occasionally, until the onion is translucent and the celery is brighter in color and a little tender, about 10 minutes.
Step 3Add the poultry seasoning and cook, stirring, for 1 minute. Add the nutritional yeast and cook, stirring, for 30 seconds. Add the stock and bring to a boil. Remove from the heat. Add the bread and parsley and fold until the bread is evenly moistened and everything is well-distributed. Season again with salt and pepper and spread the stuffing in an even layer in the prepared dish.
Step 4Bake until the top is golden brown, 25 to 30 minutes.