When I want to use a pumpkin or large squash, the first thing I do is wash it and put it into the oven on a cookie sheet with sides (I use the broiler pan which I saved from my old stove.) for about 45 minutes at 350º. Then I take it out, cut it in half and scoop out the innards. (Actually, these innards are edible and are very nutritious. Put them into the blender.) The outside of the pumpkin is now partially cooked and is easy to cut.
I put the two halves cut side down onto the cookie sheet with sides with about a cup of water and bake for about 45 minutes more.
Now it is easy to scoop the flesh from the shell.
I freeze mine in measured amounts to match what I make most. Cakes and pies!