Preheat the oven to 400 degrees.
Rinse and peel your sweet potatoes and cut them into large chunks. Place sweet potatoes in a large pot with water and bring to a boil over medium heat. Cook for 15-20 minutes until sweet potatoes are very soft.
Dice onions, mushrooms, carrots, mince your garlic, prepare your thyme, and drain and rinse your lentils.
While the sweet potatoes cook, add the olive oil and onions to a medium sized pan and cook over medium heat until the onions are soft and browned, about 6-8 minutes.
Add in the carrots and garlic and cook until the carrots are soft. You can cover the pan to help speed this up.
Add in mushrooms, lentils, tomato paste, ¼ tsp salt, thyme, and water. Cook until mushrooms are soft for about 4-6 minutes.
Remove the sweet potatoes from the heat. Drain the water and place sweet potatoes back in a large pot. Use a potato masher to mash sweet potatoes and add in ¼ tsp salt and ghee.
In a 10x8 pan, add your lentil mix and spread evenly. Top with the mashed sweet potatoes and spread evenly across lentils. Then sprinkle pepper and salt on top.
Cook for 20 minutes until the edges are lightly browned and top with fresh thyme, then ENJOY!