Cook the noodles according to the package directions.
Drain and pour into a large bowl.
Immediately add the butter and shredded cheese. Stir to mix while still hot. The cheese should melt. If it doesn't, put the mixture back in the pan and heat for another minute on medium, stirring constantly until the cheese has melted.
Add the cheese mix, milk, and broccoli, if using. Stir until combined.