If you want the creaminess with similarly low effort, then instead of just dumping the pasta water and stirring the "roux" ingredients directly into the pasta, use a slotted spoon to take the pasta out of the water instead of the other way around. Pour out some of the pasta water, but not all of it. Now add your butter and shredded cheese, along with some sodium citrate ("sour salt"; it's an emulsifier), in a ratio of about 2-3% (by weight) of the total mass of butter and cheese. Stir it up until creamy, and then add the pasta back. It adds about 2 minutes' time to making it, but I personally like the result a whole lot better, even when I'm super super short on time. Sodium citrate is really just magical stuff.
