Have him cook with you! He's still a little young, but there's plenty he can "help" do. Once my daughter started helping me cook, I could cook again! Plus, she eats a lot of raw veggies while we're cooking together - far more than she'd eat just sitting at the dinner table.
I got a step stool and had her stand on it so she was at a better height. She loves to help me stir, and helps me dump ingredients into a bowl, particularly when I make sauces. I talk her through the process and measurements. It's too early for her to really grasp math, I'm sure, but I'll say, "We need 1 teaspoon, and this is a 1/2 teaspoon. So, we'll need two of these to equal 1 teaspoon." Or we'll count things, like 3 cups of something, one at a time. It at least starts her thinking about it. I probably didn't start this until she was closer to two, but I think I could have earlier, and I certainly will with the next child.
If all else fails, I'll admit to letting my daughter watch an episode of Elmo or Wiggles at about that age. It was 20 minutes, and it at least gave me a little time!