Hearty Lentil Shepherd's Pie

1. Boil the cubed potatoes until very tender. Drain, then mash with plant-based milk, vegan butter, salt, and pepper until smooth and creamy. Set aside. 2. While potatoes cook, heat olive oil in a large oven-safe skillet or Dutch oven over medium heat. Sauté onion, carrots, and celery until softened, about 8-10 minutes. 3. Stir in the rinsed lentils, vegetable broth, tomato paste, and thyme. Bring to a simmer, then reduce heat, cover, and cook for 25-30 minutes, or until lentils are tender. 4. Stir in the frozen peas. Taste and adjust seasonings as needed. 5. Preheat oven to 375°F (190°C). 6. Carefully spread the mashed potato topping over the lentil mixture, using the back of a spoon or a fork to create peaks. 7. Bake for 25-30 minutes, or until the topping is golden brown and the filling is bubbly. 8. Let stand for 5-10 minutes before serving.