Here is how I make my mashed or pureed pumpkin, which I use in recipes calling for canned pumpkin!
1. Rinse your pumpkin with tap water to remove any dirt. (Our garden pumpkins like to get dirty! ;D)
2. Using a large cutting board and a large knife, cut your pumpkin in half. You may need to try different knives to see which works best, if you haven't cut raw pumpkin before. I prefer to use a thin serrated knife.
3. Scoop out the pumpkin seeds.* Cut your pumpkin unto fourths or eighths, depending on how large your pumpkin was.
4. Put pumpkin into a large pot and add water. I usually have my pumpkin almost covered with water.
5. Place lid on pan and bring it to a boil. Cook until pumpkin is soft. Remove from heat and pour pumpkin into a large strainer, or simply drain the water from the pan.
6. When pumpkin has cooled slightly, use your fingers or a utensil (I use a butter knife) to separate the pumpkin from the peel. Discard the peel and put the pumpkin into a large bowl.
7. When pumpkin is all peeled, you can either mash with a potato masher (easy) or blend in a food processer. Or, just use as-is, and stir your cake or bread (or whatever you're making) well.
Cooked mashed pumpkin can be frozen for later use.
The suggested (safest) method of canning pumpkin is to do the following:
1. Cut pumpkin in half and remove seeds. Slice into inch-thick slices and peel. Chop into one-inch cubes.
2. Place diced pumpkin in a pan wth a small amount of water, cover, and bring to a boil. Boil for 2 minutes.
3. Pack hot pumpkin into clean canning jars, adding liquid to fill in the cracks, up to 3/4-inch from the top of the jar. Place canning lids on and process in pressure canner for 55-minutes (pints) or 90 minutes (quarts).
However, I don't have a pressure canner. And my mom always just did it in a boiling water bath. I process my pumpkin in a boiling water bath for 3 hours (hot-packed). Experts now say that that method isn't safe, so I don't feel good about recommending it, although I will continue to do mine that way, unless I someday get a pressure canner or a chest freezer! ;)
*You can eat these seeds. Just wash them and lay on a lightly greased cookie sheet. Sprinkle with seasoned salt and bake at 300 degrees until crisp!