In a saucepan bring to boil water and add lentils. Cover and cook the lentils for 10 minutes or until tender over the medium heat. Drain and set aside.
In a large pan, heat the oil and add onion, garlic, leek, carrots, peas, green beans, mushrooms and cook for 5 minutes. Then add all the spices and cooked lentils and cook for another 3 minutes. Taste and add salt and pepper.
Preheat oven to 200 degrees Celcius.
Transfer the cooked lentils and vegetables into your casserole dish. You don't have to put baking paper or grease the casserole dish.
In a saucepan, bring water to boil and add your purple sweet potatoes. Boil them for 10 minutes or until they are very tender so you can mash them with a fork. Drain them and place them back in a hot saucepan.
In the same saucepan with your sweet potatoes, add the butter. Don't cook it, the butter will melt without cooking. Add your plant-based milk and mash the potatoes with a fork until they are absolutely smooth without any lumps.
Place the mashed potatoes on the top of lentil and vegetable mix in the casserole dish. Bake the pie in the oven for 20 minutes.
Divide in between plated and garnish with chopped fresh parsley.
Enjoy!