Place the potatoes in a large pot and fill with cold water until they’re just covered. Bring to a boil over medium-high heat and cook for 20 to 30 minutes, or until a fork easily pierces through.

Drain and transfer to a mixing bowl. Using a masher or two forks, mash the potatoes with the butter until fluffy. Season with salt and pepper, and set aside.

In a large saucepan or pot, heat the oil over medium heat and sauté the onions until translucent. Add the garlic and stir.

Add the lentils and water. Bring to a boil and season with the cumin, onion powder, salt, thyme, and pepper.

Cover the pot, reduce heat to low, and simmer for 35 minutes. Add the peas and carrots and cook for another 10 minutes. Stir in 2 to 3 tablespoons of mashed potatoes and remove from heat.

Preheat oven to 425°F. Transfer the lentil mixture to an 8- x 8-inch baking dish.

Serve hot.

Gently top with the mashed potatoes. Dot the potatoes with butter and bake at 425° F for 30 to 45 minutes, until most of the liquid is absorbed.