I have a book that is now out of print called "Ten Minutes to Table" (recipes took me about 30 mins rather than 10 until I'd had a lot of practice and some of it is frankly a bit more ambitious than you'd want to be cooking for kids). One of our favourites was pea and mint soup:
Boil stock, add frozen peas, after five mins, whizz it up, lobbing some mint and cream cheese in at the same time.
We do that with cheese on toast.
Also from that, spring pasta:
Put on tagliatelle to cook, with a veg peeler scrape a courgette into strips over the tagliatelle pan, add some frozen peas, put some cream cheese, herbs, lemon in a bowl, tip the contents of the drained saucepan into the bowl and mix.
I do variants of Jamie Oliver's cheats pizza in about 20, and put on stuff like frozen leeks and sweetcorn (hidden under the cheese, mwahaha).
Frozen onions are the way forward for cooking quickly.