Deb is fake mashed potato. It also goes very very gluey unless made up veerry carefully and not stirred too much. I wouldn’t bother with it. For shelf stable spuds, buy brushed potatoes, put them in a brown paper bag with a dry wettex/foam sponge in your fridge crisper drawer - they will last 6 months at least and maybe longer. Toss any that grow green sprouts or get very wrinkly, but most will still be good at least that long and will taste much much better than Deb. Also a shittonne cheaper. If you can, go to Vic Market and get a 5kg bag which will last a long time.

Also, for the absolute best mashed spud, chop well-scrubbed brushed spuds into largish chunks (no need to peel), put in COLD water and bring up to a boil very slowly. The 15 mins starts as the water begins to simmer. This does wunnnderful things as the cell walls of the spud slowly degrade but the starch grains don’t, so the resulting mash is never gluey and tastes intensely of potato. Once tender, press/rub through a colander or sieve and beat a bit with a wooden spoon rather than using a potato masher, then steam off residual moisture before adding salt/pepper/milk/butter/cheeee to taste.

This mix can also be used to make pretty damn nice hash browns. Chill the mash in a lined loaf tin, then slice into convenient size(s), dust with seasoned flour and fry. You can even egg/panko the slices for extra crunch. Coated slices can be frozen for instant hash browns as needed. And you are fully in control of the shape …