It's the Tom Sawyer principle of white-washing the fence.

If possible, I'd invite each child (maybe the oldest first), to join in the food preparation. Maybe with supervision, they could cut vegetables or rip the lettuce for a salad. Anything to help, even if it was small, even if it was easier to do it yourself.

Eventually, the younger ones would be curious and feel like maybe the older child was lucky. They'd feel left out and begin to insist that they could do something, too.

Before long, maybe after a week or two, everyone is engaged in meal prep. You could gently / good-naturedly invite your husband to join the family activity.

That kind of approached worked in my family when the kids were younger (my youngest is now in his 30s).

As I said before, good luck. It's vital that everyone helps carry the load, IMO.