Cook spaghetti as directed on package, adding broccoli during last minute of cook time. Drain; return to saucepan. Cover to keep warm.
Meanwhile, in medium bowl, stir together alfredo sauce and half and half.
In 10-inch skillet, cook beef over medium-high heat, stirring frequently, until thoroughly cooked; drain. Reduce heat to medium. Stir sauce mixture, cream cheese and mushrooms into beef. Cook 2-3 minutes longer, stirring frequently, until cream cheese is melted and mixture is hot.
Stir in cooked spaghetti and broccoli. Cook 1 minute longer. Sprinkle with cheddar cheese.
Test Kitchen Tip:.
Try vermicelli or linguine pasta instead of the spaghetti.