1. Preheat oven to 375°F (190°C). 2. Place 200g cubed potatoes in a pot, cover with water, add 1g salt, and bring to a boil. Cook until tender, about 15 minutes. 3. Drain potatoes and return to pot. Add 5g butter, 30ml milk, and a pinch of salt and pepper. Mash until smooth. 4. Meanwhile, heat 5ml olive oil in a skillet over medium heat. 5. Add 50g diced onion, 50g diced carrot, and 30g diced celery. Cook until softened, about 5 minutes. 6. Add 6g minced garlic and cook for 30 seconds. 7. Add 15g tomato paste and cook for 1 minute. 8. Add 150g cooked brown lentils, 60ml vegetable broth, 5ml Worcestershire sauce, 1g dried thyme, 1g dried rosemary, 1g salt, and 1g black pepper. 9. Simmer for 5 minutes until slightly thickened. 10. Stir in 30g frozen peas. 11. Transfer the lentil mixture to a small baking dish. 12. Spread the mashed potatoes over the top. 13. Bake for 20-25 minutes until golden and bubbly.