Ah yes, the smug European that has no idea that macaroni and cheese originated in Italy in the 14th century, was extremely popular in England from the 18th century, and was introduced to the US via France.
And yes, it’s cheese. Probably cheddar. You start with a bechamel and incorporate cheese to make a mornay sauce. Combine the sauce with the pasta and serve.
Alcohol is so hydroscopic that your 99% will be 91% pretty quickly after opening. 91% is fine, even 70% will do, it just takes a bit longer to evaporate.
The “impurity” is straight up water.