It sounds fine to my ear. A lot of people like to eat hot pie, cobbler, and cake right out of the oven. Though I prefer my cake warm and my pie hot, they're all delicious with ice cream on top! Since "חם" can mean both "warm" or "hot", I can have my cake either way with the cream on top.
Now I see DL has put an "a" in the sentence, which changes the meaning of the sentence. Without the "a" the meaning of the sentence is general as opposed to specific, "I want to eat cake", like "I want to drink coffee" as opposed to "I want to eat a piece of cake" or "I want to drink a cup of coffee". Now, if you say "I want to eat a cake" it means you want to eat the whole cake, and if you say "I want to eat a hot cake" it means you want to eat a whole cake that happens to be hot. If "hotcake" were one word, it would mean you want to eat one pancake. "She wants hot cake" just means she wants cake that is hot, as opposed to "She wants a piece of hot cake" which tells you specifically how much cake she wants. The way DL is writing the English sentence now means she wants a whole cake that is hot. This discussion has made me hungry. I'm off to get hot coffee and cake right now, no "a" needed!