Peel apples and remove cores.
Chop apple into small, even sized pieces.
Put apples in a pot and add water. You want just enough water to get a nice simmer in the bottom of the pan - you don't want to cover the apples in water.
Start cooking apples over medium heat to get it all hot. Once the water starts to simmer, reduce heat to low.
Cover and simmer for about 15-20 minutes, checking water level occasionally to make sure it doesn't boil dry.
Once apples are nice and soft, remove from heat and either use a vegetable masher to mash them all up, or puree them using a blender or stick mixer.
Store in the fridge for up to a week or in the freezer for up to two months.