Cut chicken into 1-inch cubes. Cook pasta according to package directions and drain.
Use a large skillet, saucepan, or Dutch oven that's large enough to hold the pasta too. Spray your pan with non-stick spray. Season chicken with pepper, garlic, onion, salt, and cayenne pepper. Add the seasoned chicken to your large pan and cook, stirring often 5 to 6 minutes until chicken is cooked through.
Add cooked pasta, cream of mushroom, chicken broth, sour cream, and 1.5 cups cheese to the pan with the chicken and stir to combine. Top with remaining ½ cup cheese.
Cover pan and simmer 5 to 8 minutes or until everything is heated through and cheese on top is melted.