Boil the Potatoes: Place the peeled and chunked potatoes in a large pot and cover them with cold, salted water.

Cook Until Tender: Bring the pot to a boil over high heat, then reduce to a steady simmer. Cook for 15-20 minutes, or until the potatoes are very tender.

Drain and Dry: Drain the potatoes thoroughly in a colander. Return the empty pot to low heat for a minute to evaporate any remaining water.

Mash to Perfection: Mash the potatoes until smooth.

Add the Richness: Add the room temperature butter, warmed milk, optional nutritional yeast, salt, and pepper. Gently stir or fold everything together until just combined.

Sauté the Aromatics: Heat the olive oil in a large pot over medium heat. Add the chopped onion, carrots, and celery. Cook for 8-10 minutes until softened.

Brown the Mushrooms and Garlic: Increase the heat to medium-high. Add the chopped mushrooms and cook for 5-7 minutes. Add the minced garlic and cook for another minute.

Toast the Tomato Paste: Add the tomato paste to the pot. Stir and cook for 1-2 minutes until it darkens in color.

Deglaze the Pan: Pour in the red wine to deglaze the pot. Let the wine simmer and reduce by about half.

Simmer the Lentils: Add the rinsed lentils, vegetable broth, soy sauce, Marmite, dried thyme, rosemary sprig, and bay leaf. Stir everything together well.

Cook Until Tender: Bring the mixture to a boil, then reduce the heat to a low simmer. Cover the pot and let it cook for 35-45 minutes.

Final Touches: Once the lentils are cooked, remove the pot from the heat. Stir in the frozen peas and season generously with salt and black pepper.

Preheat Oven: Preheat your oven to 400°F (200°C).

Assemble the Pie: Pour the finished lentil filling into a baking dish. Spread it out into an even layer.

Top with Potatoes: Spoon the mashed potato topping over the lentil filling.

Create Texture: Use the back of a fork to create ridges on the top.

Bake to Golden Perfection: Bake for 25-30 minutes, or until the filling is bubbling hot and the potato topping is golden brown.

Rest and Serve: Remove the pie from the oven and let it rest for at least 10 minutes before serving.