I've been cooking with my daughter since she was in kindergarten. I found that if she was part of the process she was way more likely to try new things. She's now 13 and can pull together a full family meal by herself. Cooking and baking are two different skill sets though. I love to bake bread but there is more than just following a recipe to make a good loaf of bread. You need to make a lot of bad ones on your journey to making good ones, it's a learning process
My work gifted me a decent amount to homechef.com and while I was originally perturbed, as I know how to cook and it was a subscription service, they were actually really good meals. I did most of the prep and my daughter brought everything together. The meals are well thought out and the instructions are very clear. It's easy to skip weeks but we still order about once a month or so. It's fun cooking in the kitchen with your teenager
What kind of baking does he like? Yeast breads, cakes, cookies, muffins? A nice set of baking sheets is always nice. And/or muffin pans, loaf pans, etc... a new set of bakeware is always a great motivator