In Harry Potter and Torah there is a chapter that explores whether performing real magic (such as creating fire) would be considered a violation of the Sabbath. The conclusion, based on writings in the Talmud and Jewish law, is that magic may violate the Torah's prohibition of non-Jewish sorcery, but is not considered "constructive work" (melacha in Hebrew) that is prohibited on Shabbos.
In yesterday's Torah portion, Beshalach, I saw a discussion of this that I hadn't seen before. As I discussed previously (click here), the manna that the Jews ate in the desert for 40 years could magically change to taste like whatever the person eating it wanted it to taste like. The book Talelei Orot (p252) quoted a Midrash that said that this included the method of preparation: if the eater wanted it to taste baked, it would taste baked, and if the eater wanted it to taste cooked, it would taste cooked. The Torah says explicitly that the manna had to be baked or cooked before Shabbat, leading to the conclusion that magically making the manna taste cooked or baked would be considered a violation of the Sabbath.
So the sources quoted by Talelei Oros seem to contradict what I wrote in the chapter in Harry Potter and Torah.
I think, however, that the Midrash quoted in Talelei Oros is a minority opinion. Rashi's commentary to the Torah interprets the verse about cooking and baking the manna (Ex 15:23) differently: "Whatever you want to bake in the oven, bake today (on Friday) for two days, and whatever you need to cook in water, cook today (on Friday). Baking refers to bread, and cooking to boiled things." Rashi specifically is saying that the Torah's prohibition of cooking and baking on the Sabbath is true baking in an oven or cooking in water, not to causing the manna to be cooked or baked through thought.
I haven't yet looked at more commentaries on the Midrash to see if this is discussed, but it seems that Rashi's commentary is consistent with all the sources in Torah writings that I quoted in the book, that conclude that magical acts are not prohibited on Shabbos, and that the Misrash quoted in Talelei Orot must be a minority opinion.
I'll post more if I find more on the subject.