It is unsafe to can pumpkin puree or pre-prepared pumpkin pie filling because the thick puree isn't acidic enough to prevent the formation of botulism spores. However, it's possible to can cubed pumpkin or freeze pumpkin puree.
The steps for preparing pumpkin for canning and for freezing are the same. Start by washing the pumpkin's exterior with warm water. Cut the pumpkin in half, and scoop out the seeds.
There are several methods for cooking a pumpkin. One is to place the halves of the pumpkins into a microwave-safe bowl with 2 inches of water in the bottom. Cover the bowl, and cook the pumpkin on high until it gets soft.
Alternatively, cut the pumpkin into quarters, and place them in a steamer basket over a pot of boiling water. Steam for 20 to 30 minutes or until soft. Another option is to bake pumpkin quarters in the oven at 350 degrees Fahrenheit for 45 minutes.
To can the pumpkin, use a sharp knife to remove the flesh from the peel. Cut the pumpkin into 1-inch cubes, being careful not to mash the flesh. Fill sterilized jars with the cubes and boiling water, leaving 1 inch of headspace. Process the pumpkin in a pressure canner at 10 pounds of pressure for 55 to 90 minutes, depending on the size of the jar.
To freeze the pumpkin, remove the flesh from the peel, and puree it in a food processor. Pack the puree into freezer-safe bags or canning jars, and store it in the freezer.