In a large pot, heat olive oil over medium heat.
Add onion, celery, carrots, and garlic. Cook until vegetables are softened.
Add corn, green peas, veggie crumbles, tomato paste, and water. Stir well.
Pour in vegetable stock and bring to a simmer.
In a separate pot, melt butter over medium heat.
Whisk in flour to create a roux.
Slowly whisk in milk to create a thick sauce.
Season with soy sauce, rosemary, salt, and white pepper.
Pour sauce over the vegetable mixture and stir well.
Preheat the oven to 400°F (200°C).
Transfer the vegetable mixture into a baking dish.
Top with mashed potatoes.
Bake for 25-30 minutes or until the potatoes are golden brown.
Serve hot and enjoy!