Frozen butternut squash!
This might not be a revelation to some, but I didn't know it existed until I discovered it lurking in the frozen foods section of Waitrose this week. At £1 for 500g, it's a great price too.
I love butternut squash (which is a fruit, not a vegetable!) but unfortunately, the rest of the family aren't so keen, so I don't buy it that often. Now I have a bag of the stuff in the freezer and can pull out a few chunks anytime I want to. I have some roasting in the oven as I type!