1. Preheat your oven to 350°F (175°C). Spray a 9×13-inch baking dish with non-stick spray and set aside.
2. In a large skillet over medium-high heat, brown the ground beef. Season with garlic powder, seasoned salt, and black pepper.
3. When the beef is halfway cooked, add the diced onion, red bell pepper, and green bell pepper. Sauté until the veggies are soft and tender.
4. Meanwhile, cook the penne pasta according to package directions until al dente. Drain and add the pasta to the prepared baking dish.
5. Pour the beef and pepper mixture over the pasta and toss gently to combine.
6. Pour the Alfredo sauce evenly over the pasta mixture and top with shredded cheese.
7. Cover the dish with foil and bake for 25 minutes, or until bubbly and the cheese is fully melted.

To make the Garlic Alfredo Sauce:

1. In a medium saucepan over medium heat, melt the butter, cream cheese, and heavy cream together, stirring until smooth.
2. Stir in garlic powder and grated Parmesan cheese. Bring the mixture to a slight boil, then reduce the heat to low.
3. Continue stirring until the sauce thickens, about 2 minutes. Season with a pinch of black pepper and remove from heat.