- Preheat the oven to 350°F. Lightly spray a 9 × 13-inch baking dish with olive oil.
- In a large bowl, stir together the soup, yogurt, and nutritional yeast. Stir in the sauerkraut, onion, and hash browns. Spread out the mixture in the prepared baking dish. Bake for 15 minutes.
- While the casserole is baking, combine the cornflakes and melted butter in a medium bowl. After the casserole has baked for 15 minutes, spread the cornflakes over the top and return to the oven.
- Bake for 15 minutes more, or until the casserole is bubbly and the cornflakes are crispy and golden. Remove from the oven and let rest for 5 minutes before serving
- Leftovers will keep in an airtight container in the fridge for up to 4 days.