Start by rinsing the lentils under cold water, then simmer them in vegetable broth until tender but still holding their shape, about 20-25 minutes. As they cook, you'll notice a gentle bubbling and a fragrant earthy aroma filling the kitchen.
While the lentils cook, peel and dice the carrots and onion into uniform pieces—this helps them cook evenly and creates a colorful base for the filling. Set aside.
In a large saucepan, heat a tablespoon of oil over medium heat, then add the diced onion and carrots. Sauté until they soften slightly and the onions become translucent, about 5-7 minutes, releasing a sweet aroma.
Add the tomato paste and herbs to the sautéed vegetables, stirring well to coat everything evenly. Let it cook for another 2 minutes until the mixture is fragrant and slightly thickened.
Drain the cooked lentils and add them to the vegetable mixture. Mix thoroughly, then season with salt, pepper, and a pinch of smoked paprika if desired. Let the filling simmer gently for 10 minutes to meld the flavors and thicken slightly.
Meanwhile, cook the peeled and chopped potatoes in a large pot of boiling water until they are very soft and easily pierced with a fork, about 15-20 minutes. Drain well.
Mash the cooked potatoes using a potato masher or fork, then stir in the butter and warm milk until the mash is smooth, fluffy, and creamy. Season with salt and pepper to taste. Set aside.
Preheat your oven to 400°F (200°C). Spread the lentil filling evenly into a baking dish, then carefully spoon the fluffy mashed potatoes over the top, spreading them out with a spatula to create an even layer.
Place the assembled pie in the oven and bake for about 20-25 minutes, until the top is golden brown and slightly crispy around the edges. The filling should be bubbling as it bakes.
Remove from the oven and let it rest for 5 minutes before serving. The aroma of baked potatoes and savory filling will invite everyone to dig in. Serve warm and enjoy the comforting layers of flavor and texture.
