Preheat oven to 200C.
Add the potatoes to a large pot of boiling water. Cook until tender soft. Drain and mash with the dairy free milk until the are no lumps and is light and fluffy. Season with salt and pepper. Set aside until ready to use.
Meanwhile, in a fry pan heat the olive oil over medium to high heat. Sauté the onion and garlic for 5 minutes or until onion is tender.
Add carrots, celery and peas and continue to sauté for a few more minutes, stirring occasionally.
Add spices, sauté for a minute or until fragrant.
Add lentils and tomato paste, stir quickly and add vegetable stock. Season with salt and pepper to taste.
Cover and raise the heat to bring to a boil. Reduce heat and simmer gently for 20 - 30 minutes.
Check the stock levels and lentil consistency. Cook for another 10 - 15 minutes if lentils are not cooked.
Remove from heat and allow to cool slightly. Note, the mixture should be moist but not swimming in water. If the mixture is too wet, simmer for a small amount of time with the lid off.
Add the lentil filling a lightly greased casserole dish.
Spoon over the mashed potato and brush the top with 1 tbsp of olive oil, season with a little freshly cracked salt and pepper.
Bake in the oven for 30 to 40 minutes or until golden brown on top.
Serve immediately with either a serving of lightly steamed greens or side salad of choice.