I've been working full-time for over a year now. Most evenings I get home not too exhausted and a healthy dinner with all the major food groups gets made. Some days, it does not.
When Boyfriend doesn't feel like covering (we swap kitchen duties every other day), we have our go-to low-effort meal: Mac & Cheese with Other Stuff Added.
Other stuff can be whatever you want, although I usually go for sausage (Aidell's Cajun Style Andouille is a particular favorite). I saute the sliced sausage with either broccoli or green beans in olive oil until everything browns and caramelizes and add it to boxed macaroni and cheese, cooked according to whatever the side of said box says (we like Annie's Cheesy Taco Mac and Cheese best, but it's hard to find in our little Safeway. I add Cajun seasoning if I can't find it.).
It's filling, at least mildly nutritious, and only takes ten minutes from start to finish.