For me, there is nothing more fun (or messier) than cooking with my kids. I've been doing it with both of them since they were each about a year old, and I've learned a lot since then. Here's what I know:

Why cook with your kids?

• It makes them invested in what they're eating. If they made it, they'll more than likely want to eat it.
• It's creative!
• It's one on one time that you'll both remember forever.
• It teaches them a valuable, life-long skill.

How can you get your little ones involved in the kitchen safely?

• Set up some ground rules first. Only Mommy handles the knives, pans, stove, oven, mixer, etc.
• Set up a sturdy stool or chair to get them to counter level (I like the "Learning Tower"; it's one of the best investments I've ever made).
• Give them their own tools to work with. Whisks, spoons, spatulas, bowls, measuring cups, spoons, etc.

Tips:

• Pick a recipe together from a cookbook, magazine or blog that has pictures of the finished product. Make it something they're interested in! My advice? Start with cookies. Every kid loves cookies. If they're still with you when the dough is going in the oven, next week move on to a dinner dish. Breads and other doughs that need to be kneaded (homemade pizza: an all-time kid favorite!) are hilariously messy and fun.
• Make a shopping list, and let them help you find the items at the store (cutting out pictures from the weekly circulars and making a "scavenger hunt" is always a hit!)
• Before you start, explain which steps of the recipe they can help you with (this will vary depending on the age of your child), and which ones only a grownup can do.
• Talk about the steps as you go along. Make it an adventure that you're taking together. Ask, "Why do you think we need to cut the onion into small pieces?" or "What's going to happen when it goes in the oven?" Cooking is science in many ways, and it can be a great learning experience.  
• Expect a mess. A big one. And for a 20-minute recipe to take an hour. Be okay with it.
• Have fun. Cooking should be fun, anyhow!
• If you already cook with your kids: next time you're in the grocery store, have them pick one (healthy) item that they've never had before. Take it home, and figure out together what to cook with it. Using this simple trick, my daughter has tried beets, purple barley, rainbow chard, star fruit and jicama! Sure, she hasn't liked all of it, but she's tried new things. That's the important part.

Do you cook with your kids? What do you (or they) like to make?