Cook cavatappi with tablespoon salt to 1 minute short of package time. Reserve 1 cup pasta water; drain.
Meanwhile, cook bacon in large skillet 6 to 8 minutes until crisp. Plate; leave 1 tablespoon drippings.
Season chicken with its salt and pepper; cook in drippings 6 to 8 minutes until browned and at least 165°F. Transfer to clean plate; keep skillet over medium-low.
Melt butter; stir flour 1 minute. Gradually whisk in milk and broth; add herbs, garlic powder, and onion powder. Simmer 3 to 4 minutes until lightly thickened.
Remove from heat; melt cheddar into sauce. Add pasta, chicken, bacon, and 1/4 cup reserved water. Return to low 1 minute to finish pasta, adding water if needed; serve.