Today's recipe for Cheese & Potato Pie Sausage Rolls is so easy, and uses leftover mashed potato, OR a sachet of instant mashed potato. It's based on my mum's recipe for CHEESE AND POTATO PIE, but uses fresh spring onions in the filling. I always have instant mashed potato in my store cupboard - I use it to thicken soups and stews, as well as for small portions of bangers and mash, or cottage pie. Modern instant mashed potato isn't like it used to be in the Smash potatoes days - it's hard to notice the difference between freshly boiled spuds and the instant. And, with energy prices rising, all you need to do is boil a kettle, and add 300ml of boiling water to an 80g sachet of instant mash.