I have just discovered frozen mashed potato and it's revolutionary!
I was dubious and thought surely it's full of added crap but it's not. It comes out so creamy and fluffy and tastes lush. No more peeling potatoes for me! I bought a bag from Iceland for about 90p. There may be some fancier versions and mash made from actual potatoes may be more cost effective but I don't care!
What's your ultimate lazy food shortcut?