Rinse the lentils and add them to a pot with 4 cups of vegetable broth. Bring to a boil, then simmer until tender, about 20–25 minutes.

In a large skillet, heat 2 tablespoons of olive oil over medium heat. Add diced onion, carrots, and celery. Sauté for about 5 minutes until softened.

Stir in the mushrooms and minced garlic. Cook for another 5 minutes until everything is fragrant and tender.

Add the cooked lentils, tomato paste, red wine (if using), thyme, rosemary, bay leaf, peas, corn, and soy sauce. Season with salt and black pepper. Stir and let it simmer for 10 minutes.

While the filling simmers, boil the peeled potatoes in salted water until fork-tender, about 15-20 minutes. Drain, then mash with plant-based milk, vegan butter, nutritional yeast (if using), and salt and white pepper to taste.

Preheat your oven to 400°F (200°C). In a baking dish, spread the lentil mixture evenly. Top with the mashed potatoes, smoothing it out.

Bake for about 25 minutes or until the top is slightly golden and crispy.

Remove from the oven and let it cool for a few minutes before serving. Don't forget to take out that bay leaf!