Preheat the oven to 350°F (175°C). Grease an 11x7 or 9x13-inch baking dish. Cook the pasta in salted water, draining it 1 to 2 minutes before al dente. Set aside.

Toss the cubed chicken with olive oil, paprika, garlic powder, onion powder, and salt. Heat a large skillet over medium-high heat and sear the chicken for 10 to 12 minutes until fully cooked. Transfer to a plate.

In the same skillet, reduce heat to medium and melt the butter. Sauté the onion and garlic for 2 to 3 minutes until softened and fragrant. Sprinkle in the flour and whisk continuously for 1 to 2 minutes to cook out the raw flour taste.

Slowly pour in the heavy cream while whisking constantly to prevent lumps. Simmer for about 5 minutes, stirring regularly, until the sauce thickens enough to coat the back of a spoon.

Stir in the Parmesan cheese, garlic powder, salt, and 1/4 cup of the shredded mozzarella until the sauce is smooth and glossy.

In a large bowl or directly in the baking dish, fold together the cooked pasta, seared chicken, and raw broccoli florets with the alfredo sauce until evenly coated.

Spread half the mixture into the baking dish and sprinkle with 1/2 cup of mozzarella. Top with the remaining pasta mixture and finish with the final 1 cup of mozzarella spread evenly across the top.

Bake uncovered for 30 minutes until the cheese is golden and the sauce is bubbling around the edges. Let the bake rest for 5 minutes before serving.