Prep the oven and pan. Preheat to 375°F (190°C).
Lightly grease a 9x13-inch baking dish.
Par-cook the broccoli. Steam or microwave the broccoli until crisp-tender, about 2–3 minutes. Drain well and pat dry so the bake doesn’t get watery.
Make the creamy sauce. In a saucepan over medium heat, add butter or oil. Sauté garlic for 30 seconds until fragrant.
Whisk in cream cheese, heavy cream, and chicken broth. Stir until smooth and gently bubbling.
Season the sauce. Add onion powder, Dijon, smoked paprika, salt, and pepper. Stir in 1 cup shredded cheese and the Parmesan until melted.
Taste and adjust seasoning. Add a squeeze of lemon if you like.
Combine in the dish. Add chicken and broccoli to the baking dish. Pour the sauce over and toss gently to coat everything evenly.
Top with cheese. Sprinkle the remaining 1 cup shredded cheese over the top.
Bake. Place in the oven for 18–22 minutes, until the edges bubble and the top is melted and lightly golden.
Rest and garnish. Let it sit for 5 minutes to set.
Finish with chopped parsley or chives.
Serve. Enjoy as is, or pair with a simple green salad or cauliflower mash.