Make the filling

• Start by preparing your ingredients: Peel and halve the onion, finely chop in a food processor, and set aside in a bowl. Peel the carrots, cut into a few large chunks, finely chop in a food processor, and set aside in a separate bowl. Wash and trim the mushrooms, finely chop in a food processor (in multiple batches if needed), and set aside in a separate bowl. Press or mince the garlic.
• Melt 2 Tbl butter on medium low in a large heavy bottom pot or Dutch oven. Add the onions and cumin seeds. Cook for 5 minutes, stirring often. Add the carrots and garlic. Cook for 5 more minutes, stirring often.
• Add the mushrooms and salt. Mix well to combine. Increase the heat to medium-high. Let the mushrooms sweat all of their liquid, and cook until all the liquid evaporates. Stir only occasionally during this process. Then add the remaining 1 Tbl of butter and mix so it melts.
• On medium heat, add the tomato paste. Cook for three minutes, stirring often. Mix in the smoked paprika.
• Add the red wine and balsamic vinegar. Deglaze, detaching any browned bits from the bottom of the pot. Cook for about 8 minutes, stirring occasionally, until almost all of the liquid is reduced.
• Rinse your lentils and add to the pot. Pour in the vegetable broth. Mix well. Bring to a gentle simmer. Cover and cook on low for about 30 minutes, or until the lentils are tender but firm (al dente). If the mixture is liquidy, cook uncovered for about 5 minutes, or until most of the liquid evaporates. While the lentils are cooking, set your oven to the broil or grill setting at 450 ℉ (230 ℃), and prepare the potato layer.

Prepare the potato layer

• Peel and cube the sweet potatoes and potatoes. Steam or boil them together until very tender.
• In a large bowl, mash the potatoes until smooth. Mix in the butter, milk, salt, and parmesan cheese.

Assemble and broil

• Lightly grease a deep baking dish measuring about 8 x 10 inches (25 x 21 cm).
• Pour in the filling, leaving 1½ inches (4 cm) space at the top for your potato layer. If you have leftover filling, you can reserve it in the fridge for a different use.
• Spread the mashed potatoes on top of the filling. Score with the back of a fork to create a slightly ridged texture.
• Mix together 2 Tbl of grated parmesan cheese and 2 Tbl of breadcrumbs. Sprinkle on top of the potato layer.
• Add the dish to the middle of your preheated oven for a few minutes, until the top turns golden brown. Keep a close eye for burning.
• Remove the dish from the oven and let it sit for 5-10 minutes to solidify.

Enjoy!