We're in an obesity epidemic and most people don't know how to cook even very basic meals.
Make space for it, squish other classes if you need. Make it mandatory, everyone has to take it. Maybe even ongoing through multiple grades.
Edit: Rice, beans, and even basic meats are cheap. To eat healthy you don't need your meal to be 100% Bell peppers and tomatoes.
I really don’t think this would cost much overall in society.
It even goes the other way: Compared to the costs of obesity and its effects, this would save money.
And this is the unpopular part: get it done. Cut whatever other class you need to, increase taxes, get it done.