Bring a large pot of lightly salted water to a boil. Add pasta, and cook for 8 to 10 minutes, or until al dente. Add the asparagus during the last 3 to 5 minutes of cooking. Drain, and transfer to a large bowl.
In a large saucepan over medium heat, combine butter and half-and-half. Cook until thick and bubbly. Season with garlic powder, black pepper, and cayenne pepper. Stir in Parmesan cheese and chicken, and heat through.
Pour sauce over pasta and asparagus, and toss to coat.
