01 - Preheat the oven to 400°F. Grease a 9x13 inch baking dish.
02 - Boil salted water and cook pasta until just al dente. Add broccoli florets during the last 2 minutes of cooking. Drain and set aside.
03 - In a large skillet over medium heat, sauté diced chicken seasoned with salt and pepper until fully cooked, about 6 to 7 minutes. Remove from heat.
04 - Melt butter in the same skillet over medium heat. Add minced garlic and cook until fragrant, about 1 minute.
05 - Whisk in flour and cook for 1 minute. Gradually add milk and cream while whisking continuously until smooth. Cook until sauce thickens, about 3 to 4 minutes.
06 - Stir in Parmesan, mozzarella, salt, black pepper, and Italian herbs if using. Remove from heat once cheese has melted and the sauce is creamy.
07 - In a large bowl, mix cooked pasta, broccoli, chicken, and Alfredo sauce until evenly coated.
08 - Pour mixture into the prepared baking dish. Evenly sprinkle remaining mozzarella and Parmesan cheese over the top.
09 - Bake uncovered for 20 to 25 minutes until the cheese topping is golden and bubbly.
10 - Allow to rest for 5 minutes before serving to set.