Cut the spaghetti squash lengthwise in half and bake in the oven on a baking sheet until the skin is soft, about 45 minutes. Once the squash is cooked, scoop out the meat with a spoon into a large baking dish. Add your pasta sauce and meatballs onto the squash.
If the sauce is still frozen, don't worry about it. It's not a big deal.
Add your cheese and butter, then bake in the oven for another 30 to 45 minutes.
Once it's cooked, I suggest using a turkey baster to suck out some of the excess liquid that comes from the sauce.
Enjoy!