Honestly, there are some slow cooker recipes that take just a few minutes to throw together.
My 3 year old loves a salad I make with toasted nuts (either pecans or walnuts), cut up apple, and a quick dressing I make with olive oil and apple cider vinegar, honey, salt and pepper. Normally she doesn't like salad but she likes the sweet dressing and the nuts and apples.
Also things like quesadillas are great, as are beans and rice:
http://allrecipes.com/recipe/black-beans-and-rice/.
I made a really simple vegetable lasagna recently - doesn't take long to put together - just cook on a weekend day or cook the night before for dinner for the next few nights. The veggie lasagna recipe was posted in this forum recently (I asked for it and got it) if you go back a page or two.