Prep the oven and dish: Heat the oven to 400°F (200°C). Grease a 9x13-inch baking dish.

Prep the cauliflower: Cut cauliflower into bite-size florets. Toss with olive oil, salt, and pepper on a sheet pan.

Roast to tender-crisp: Roast 18–22 minutes, stirring once, until just tender with a little browning. You want some bite so it holds up in the bake.

Make the Alfredo sauce base: In a large skillet over medium heat, melt butter. Add garlic and cook 30–60 seconds until fragrant.

Add cream and broth: Pour in heavy cream and chicken broth. Bring to a gentle simmer, then reduce heat to low.

Whisk in cheeses: Add cream cheese in small pieces, whisking until smooth. Stir in Parmesan. Simmer 3–5 minutes to thicken slightly. Season with 1/2 teaspoon salt, 1/2 teaspoon pepper, 1/2 teaspoon onion powder, and 1 teaspoon Italian seasoning. Add a pinch of red pepper flakes if you like heat.

Combine with chicken: Stir the cooked chicken into the sauce and warm through. If the sauce seems too thick, add a splash more broth or cream. It should coat a spoon but still flow.

Assemble the bake: Add roasted cauliflower to the baking dish. Pour the chicken Alfredo mixture over top and gently fold to coat. Sprinkle shredded mozzarella evenly over the surface.

Bake: Lower oven temperature to 375°F (190°C). Bake 18–22 minutes, until the edges are bubbling.

Broil for color (optional): Broil 1–2 minutes to brown the cheese lightly. Watch closely so it doesn’t burn.

Rest and serve: Let it sit 5–10 minutes to set. Garnish with chopped parsley and a little extra Parmesan. Serve warm.