In a large pot over medium high heat, cover the potatoes and parsnips with water by a few inches. Bring to a boil and allow to cook for 30-35 minutes, until they are very tender enough to be mashed.

Meanwhile, start the filling but warming the olive oil in a dutch oven over medium heat. Add the onion, sprinkle with salt and cook for a few minutes. Add the garlic, carrots, mushrooms, celeriac and seasonings (thyme and oregano) then cook for about 5 minutes, until the mushrooms start to release their liquid. Pour in the red wine, tomato paste, and Worcestershire and bring to a boil. Allow to cook for about 5 minutes.

Next add the rinsed lentils along with the vegetable broth and bring to a boil. Reduce heat to low then cover and allow to simmer for 30-35 minutes, until lentils are tender.

Preheat the oven to 400°F. Drain the water from the potatoes and parsnips. Using a potato masher or fork, mash the potatoes and parsnips together. Add the vegan butter, milk, garlic powder, and salt & pepper to taste.

Lightly grease a pie dish or large casserole dish then fill the bottom with the lentil mixture. Top with a layer of parsnip mashed potatoes, spreading them evenly so that they cover the lentils.

Cook in the oven for 20-30 minutes, until the potatoes are a light golden color. Allow to cool for five to ten minutes then sprinkle with chives and pepper. Serve warm and enjoy!