Choose a topic. If you're going to teach people to make Italian food, for example, come up with a good range of dishes to present. Do some research. Perhaps choose a region of Italy or a time period. Don't go for the expected pizza and pasta. Try a muffaletta (a layered meat, vegetable and cheese dish) or a panettone (a traditional Italian Christmas cake).
Write an outline for your script before writing the actual script. Break the script down into three acts, like the beginning, middle and end of a story. Tell the audience who you are, what you plan to cook, what they need to prepare the dish themselves, then how to make it. Give your audience a mix of practical information and personal and informative anecdotes. Make each part of your script engaging, creative and succinct.
Write a script that is an appropriate length for your topic. Most cooking shows are half an hour, which theoretically means the script should be about 22 pages long. However, the length of a cooking show script tends to be less because it usually involves only one person talking to the camera. So for a half-hour cooking show your script should be about 15 pages long.
Format your script correctly. Either use a screenwriting program like Final Draft or write it in Microsoft Word but copy the proper structure and page layout from a real script. You can look at real scripts on websites such as Drew's Script-O-Rama. People will only take you seriously if you are professional. Even if this is a home project, it's easier to describe what you want to your crew if your script is in the proper format.
When writing a cooking show script, bear in mind that the viewers like to feel that you're really talking to them. Don't just explain the steps for cooking a dish. Engage your audience--think about who they are and what they want to know. Cultural information about the dish's origins, speedy cleanup techniques, good dishes for kids and how to cook gourmet-style on a budget are possible topics. Tailor your script to your audience.