Is cooking forbidden on Sundays?
Canon law forbids only unnecessary manual labor. Hence, if you are a baker at a bakery, and you work five or six days per week, then you are forbidden to work there on Sunday, because it would be unnecessary. However, some necessary, daily manual chores in the home are permissible on Sunday, such as cooking, or cleaning the dinner table, etc. In fact, if your mother decides to cook a nice meal every Sunday for the family, she is not violating canon law; that is allowed. Her cooking would be ordered to a proper observance of the Lord's Day. Also, anything else that involves manual labor but is ordered to the propery observance of the Lord's day is also permissible; for example, if you decide to iron your Sunday clothes on Sunday morning because you do not want to wear wrinkly clothes to Mass; or if your car battery dies on Sunday morning before leaving for Mass, and you are allowed to "jump" the car so you can get to Mass.
However, any manual chores that need not be done every day, or need not be done on Sunday, may not be done on Sundays. For example, one should not do the weekly house cleaning on Sunday, or gardening, or washing one's car, or home improvement, other similar manual chores. (It is--or at least it used to be--a common practice among Catholics to utilize Saturday for such chores.)
Now, some public manual functions that are necessary for the proper functioning of society are also permissible on Sundays (for example, if there is a fire on Sunday, a firefigher should not wait until Monday to put it out!). Moreover, it may be that the ONLY way a man can find work is if he works on Sunday. Some jobs are such that they do not give you any other option. If that is the case, then one is exempt and may work. This situation is rather rare, but it is a possibility nonetheless.
Also, play, even of the more physical sort, such as sports, are permissible on Sundays because they are not considered labor. Hence, you may very well play baseball or football or whatever as a form of recreation.
Now, some people who have non-manual professions, such as myself as a professor, prefer also to abstain from working those days, even though the Church does not forbid it. This is a very laudable custom, although it is not mandatory. The prohibition is only with regards manual (physical) labor. Hence there are some (such as students and teachers) who customarily use Sunday afternoon to engage in their intellectual work, and this is not forbidden.
Finally, be aware that the fact that the sabbath rest must be done specifically on Sunday is from Church law, not from divine or natural law, and hence it does not apply to those who are outside the Church. Hence, a Jew or Muslim does not sin by working on Sunday (historically, it has been quite common, for example, for Jews and other non-Catholics to take up the functions that are necessary for the normal operation of society on Sundays, such as the firefighting example above).
For more, refer to the old, catechetical gem, My Catholic Faith (the section on the Third Commandment--I don't recall the page number). It has a nice, thorough explanation of all of this.