Preheat the oven. Set your oven to 375°F (190°C). Lightly grease a 9x13-inch baking dish or similar casserole pan.

Prep the veggies. If using cauliflower, steam or microwave florets until just tender, about 4–6 minutes. Drain well and pat dry. If using zucchini, slice and lightly salt, then blot excess moisture after 10 minutes. This keeps the bake from getting watery.

Cook the beef. Heat olive oil or butter in a large skillet over medium-high heat. Add the ground beef and break it up with a spatula. Season with salt, black pepper, and Italian seasoning. Cook until browned and no longer pink, about 6–8 minutes. Drain excess fat if needed.

Sauté aromatics and mushrooms. Push the beef to the side of the pan and add onion, garlic, and mushrooms to the center. Cook 4–5 minutes, stirring, until the onions are soft and mushrooms release moisture. Stir everything together. Add crushed red pepper flakes if you like some heat.

Make the Alfredo sauce. Lower the heat to medium. Pour in the heavy cream and add the cream cheese cubes. Stir until the cream cheese melts and the sauce looks smooth, 3–4 minutes. Stir in Parmesan until it melts and thickens slightly. Taste and adjust salt and pepper.

Combine with veggies. Add the cauliflower or zucchini to the skillet and gently fold into the beef Alfredo mixture. You want everything evenly coated but not mashed.

Assemble the bake. Transfer the mixture to the prepared baking dish. Sprinkle mozzarella and a little extra Parmesan evenly over the top.

Bake until bubbly. Place in the oven and bake for 18–22 minutes, until the cheese is melted and the edges are bubbling. For a golden top, broil for 1–2 minutes at the end, watching closely.

Rest and garnish. Let the bake rest for 5–10 minutes so it sets slightly. Sprinkle with fresh parsley and serve warm.