I earn good money and she quit her career a couple of years ago and works part time in a job that’s a doddle for her and she finds it enjoyable.
I'm wondering if she's struggling under an invisible workload that you don't realise is there.
Your youngest is 7 years old, which means that your wife was looking after pre-schoolers until 2 years ago. That's a full time job - was she still working FT for part of it? So you both agreed that she would go PT to get a better family balance and maybe keep youngest out of nursery? (I'm guessing here of course)
Now both kids are in school, it will be somewhat easier for her to go back FT. Except that once you go PT it can be very difficult to get back to FT, especially if you're looking for a job that allows you to stop work at 3pm to pick up the kids. If you work for yourself, maybe she'll find it easier if she drops off and you pick up? (Which of course means all the after school childcare as well)
I acknowledge that you've been involved in childcare, however who carries the mental load? By which I mean arranging kids' activities, sorting out birthday presents for kid's parties, filling out school paperwork, paying any afterschool clubs, sorting out fancy dress days, buying school uniform, taking them shoe shopping when they outgrow shoes (mine are doing that all the time at the moment sigh), arranging/supervising playdates, taking them to dentist checkups, supervising homework etc etc The list could go on and on. Maybe you do some of it, but maybe a lot of it is invisible?
You say she does the cooking and shopping. Who does general housework? Hoovering? Laundry? Paperwork, e.g. insurance? Again, maybe you do part of this, but maybe she does?
I can hear that you're fed up, but I wonder if this is the opposite side to so many posts on here where the woman complains about being left to do all (/nearly all) the housework and childcare and the husband resents having to earn all the money while his wife 'does nothing all day'.
Have you offered to swap roles with her? You go part time (and take over any chores she's doing) and she goes full time?
Of course, it's also possible that she does none of this extra work I've been talking about, and she is indeed enjoying having a relaxing time at your expense. It's hard to tell without a fuller picture :)