1. Cook pasta in boiling salted water according to package directions. Drain and set aside.
2. Meanwhile, cut chicken into bite-size pieces. Melt butter in a large skillet over medium heat. Add chicken; cook, stirring, 4 to 5 minutes. Add garlic and continue to cook until chicken is just cooked through. Stir in flour; slowly pour in milk and broth, stirring constantly. Add salsa and cream cheese and stir until sauce is hot and bubbling and cream cheese is melted and smooth.
3. Add drained pasta to skillet; stir until pasta is coated with sauce and everything is well combined. Serve immediately.