Preheat an oven to 350F degrees.
Heat a large pot of water to boil. Rough chop the cauliflower, and boil until easily pierced with a fork.
Drain the cauliflower, and using an immersion blender, blend the cauliflower, butter, and milk until creamy. Salt to taste. Set aside.
Cook the ground beef over medium heat. Add half of the spices. Set aside.
Chop the veggies. Cook in the beef fat (if needed, add butter to the pan). Mix in the remaining spices.
In an 8x8 casserole dish or 8-9 inch skillet, place the veggies, then beef, then cauliflower, and lastly cheese if using.
Bake until everything is evenly heated and cheese is melted.
Optional: Broil for 1-2 minute to crisp the cheese.