Preheat and prep: Heat oven to 375°F (190°C). Grease a 9x13-inch baking dish.

Par-cook the veggies: Toss cauliflower florets and zucchini with olive oil, salt, and pepper. Spread on a sheet pan and roast for 10–12 minutes until just tender. This keeps the bake from getting watery.

Cook the chicken (if not using pre-cooked): Season chicken breast with salt and pepper. Sear in a skillet with a little oil over medium heat, 5–6 minutes per side, until done. Rest, then cube or shred.

Make the Alfredo sauce: In a large skillet, melt butter over medium heat. Add garlic and cook 30–60 seconds until fragrant. Whisk in heavy cream and chicken broth, then add cream cheese in chunks. Stir until smooth.

Finish the sauce: Stir in Parmesan, a pinch of nutmeg, salt, and pepper. Simmer 2–3 minutes until slightly thickened. Adjust seasoning. The sauce should coat a spoon but still be pourable.

Combine: In a big bowl, mix chicken, roasted cauliflower and zucchini, and half the mozzarella. Pour most of the Alfredo sauce over and gently fold to coat. If it looks dry, add the rest of the sauce.

Assemble: Spread the mixture in the baking dish. Top with remaining mozzarella and a light shower of extra Parmesan.

Bake: Place in the oven for 18–22 minutes, until bubbling at the edges. Broil 1–2 minutes at the end for a golden top if you like.

Rest and serve: Let it rest 5–10 minutes to set. Garnish with parsley and a pinch of red pepper flakes if using.