DaasYochid: I did some quick research on this matter and these are teh following salient points: the gemoro (shabbos 95A) says that it is a “melocho” to make cheese on shabbos (“chayiv”) because it is building something- and “boneh’ is a melocho. Tosefos deducts from this that “boneh” would NOT be a melocho that is prohibited on yomtov- because making cheese would be allowed on yom tov and hence so will this “melocho”. Tosefos prohibits,however, building a house because of “uvdo dechol”. Still ,it is clear taht making cheese on yom tov would be muttar!
The Rambam “paskens’ like this gemoro and says making cheese is a ‘melocho d’oraisa”. Interestingly ,neither the Rif, nor the Tur ,nor the Shulchan Aruch mentions this rambam and his psak. Why? Well, courtesy of Artscroll notes, it is pointed out that many Poskim hold that “boneh” is only a melocho when doing it on the ground (like a house), not on keilim and here with cheese it would be like making a kli-hence not a d’oraisa. In short, these are the rishonim on this matter.
Now, on to electricity. I checked the “SHmiras shabbos’. First of all, he clearly allows cooking on an electric burner (sima 3). However, he maintains, following the bulk of acharonim, that making an electric connection is ossur on yom tov- mainly because it is “Nolad’-starting from nothing (same as striking a match). Therefore, he also maintains that it owuld be ossur to increase or decrease an electric burner because , he says, this act either extinguishes or increases THE AMOUN OF ELECTRIC COILS.
I understand his reasoning , although I may say, that the burners I know DO NOT ADD OR EXTINGUISH individual burners- they only increase, or decrease, the ampage throught the same coils.
On to my comment about ‘boneh’ on yom tov. This was in reaction to a commenter who said that it was a mistake to say that electricty is muttar on yom tov. To which I replied that those who are mattir electricity on yom tov (and they were some pretty big Poskim)do not think it is a mistake- even if we accept the chazon ish that it is boneh! because- further to the tosefos (and the rambam), boneh would also be muttar on yom tov.
All of the above gives way to the issur on “Nolad’ on yom tov, which has nothing to do with the melocho.