Can I compile only one class files and use it?

I have a asp.net application, in which I have App_code folder with different classes. Whenever I publish my application it creates single App_Code.dll for all classes, which is fine, but now I have to add one more class but I want to publish only that class file. Is it possible??

Try with adding new project (Class library ) in solution, add your class file in that project . And use it by adding reference it to in another project.