Not really batch cooking but something I find useful is buying a load of fresh vegetables...mushrooms, peppers, onions, leeks, courgettes, okra, sweet potato, anything else I fancy really. Chop the lot, mix together well and fill a couple of zip lock bags to freeze. I can take out as many handfuls as I want to chuck into variations such as curry, bolognese, make soup, or whatever, adding extras fresh as required - chicken, mince,lentils, beans, etc, depending on what you are making. It's great for mixing with any left over stuff in the fridge for one of our "using up" meals, when there is not enough to "use up" without additions.
Re batch cooking I do curries, bolognese, cup cakes, icing, stews, macaroni cheese as some examples.