In a large pot, bring water to a boil and add a generous pinch of salt. Drop in the fettuccine and cook according to package instructions, about 8-10 minutes. Toss in the broccoli florets for the last 2 minutes of cooking. Drain and set aside.

While the pasta is cooking, heat olive oil in a large skillet over medium-high heat. Season the chicken breasts with salt, black pepper, and Italian seasoning. Cook for about 5-7 minutes on each side until golden brown and cooked through. Remove from the skillet and let it rest before slicing.

In the same skillet, lower the heat and add minced garlic, sautéing until fragrant (about 30 seconds). Pour in the heavy cream, bring to a gentle simmer, and whisk in the Parmesan cheese until smooth.

In a big bowl, mix the cooked pasta, broccoli, sliced chicken, and Alfredo sauce, ensuring every morsel is coated in cheesy goodness.

Preheat your oven to 350°F (175°C). Transfer the mixture into a casserole dish, sprinkle the mozzarella cheese on top, and bake for about 25-30 minutes, or until the top is bubbly and lightly golden.

Once baked to perfection, serve hot, and enjoy!