• Preheat oven to 400ºF, grease an ovenproof casserole dish and set aside.

Mashed Potatoes:

• Peel and chop potatoes.
• Add to pot, cover with water. Bring to a boil, turn down and simmer.
• Once cooked, drain out the water.
• Mash the potatoes, add the milk, olive oil and chives. Set aside.

Filling: (make this while the potatoes are cooking)

• In a large frying pan, heat the olive oil.
• Sauté the onion for about 5 minutes.
• Add the thyme, salt and pepper and mix.
• Add the frozen peas and carrots, and cook for about 5 minutes.
• Add the cornstarch and mix well.
• Add the lentils and crushed tomatoes. Bring to a boil and simmer for a minute or two.

Assemble:

• Place the filling in the casserole dish.
• Top with the mashed potatoes. Use a fork and spread over the filling, spread to the edges of the dish. Make some nice ridges in the potatoes to create some crispy edges while baking.
• Place the casserole dish in the oven, and bake for about 35 minutes. The potatoes will have some crispy tips, and the filling will be bubbly and starting to leak around the edges of the potatoes.
• Remove from oven and serve.