Spray some oil in a pan over medium-high heat. Saute the onions until soft (4-5 mins) and then add carrots with a pinch of salt. Cook for another 3–4 min until softened.
Add and brown your ground beef, break it up, and cook through. Add 15 g tomato paste, seasonings, and 200 ml beef stock with 150 g peas. Lower heat, cover, and simmer 10–15 min.
Boil 400 g potatoes + 400 g cauliflower in salted water for ~12–15 min or until fork-tender. Drain, return to the pot, and mash with 50 ml skim milk plus salt & pepper.
Preheat oven to 400°F. Spread the beef filling in an oven-safe dish. Top evenly with the cauliflower-potato mash. If desired, sprinkle 50 g cheese on top. Bake for ~20–25 min, until golden.
