Heat olive oil in a skillet over medium heat. Sauté diced onion and minced garlic for 3-4 minutes until translucent.
Add ground beef or lamb, breaking it apart as it cooks. Brown for 5-7 minutes, then drain excess fat.
Stir in tomato paste, Worcestershire sauce, thyme, rosemary, salt, and pepper. Pour in beef broth and add frozen mixed vegetables. Simmer for 5-10 minutes.
Steam cauliflower florets until tender, about 10 minutes. Blend until smooth, adding salt and pepper to taste.
Spread meat mixture in a baking dish, then top with cauliflower mash. Optionally sprinkle with cheddar cheese.
Preheat oven to 400°F. Bake for 20-25 minutes until golden and bubbly.
Let cool for a few minutes before serving.