peel and core the apples, put into a large bowl with just a drop of water and microwave it for a couple of minutes. stir and repeat until the apples are complete mush (doesn't take long). put into freezable containers (plastic take-away boxes are ideal) and freeze until solid then transfer to plastic bags (takes up less space in freezer) and store in freezer until needed.
useful for crumbles, pies, or just plain old apple sauce. add whatever sugar or sweetener you want when you thaw it out to use.