in a shallow baking pan place the cut and cleaned squash down on pan with 1/2" water in pan.
bake at 350 for about an hour or until squash is tender out to skin.
remove from oven and let stand to cool. Remove skins and place the squash pulp into a large bowl, all three types of squash all together.
Mash the pulp until all mixed together and smooth. This will be a lot of squash so you may want to bag and freeze most of the squash. I use 1 quart zip lock freezer bags, usually about 8 bags into the freezer.
the remaining squash can be served as is or you can add a little butter and cream to the squash and mash into squash before serving.