Hawking’s history of time actually anwsers this question with „we don’t know and don’t have any information from before big bang we can access to use in research”.
So a spaghetti god monster could have created it? It could but you would never be able to prove it.
The only observation is that currently we don't know. Could it be the spaghetti god monster? Maybe. Maybe not. We simply can't tell at the moment.
There are things we don't know the answer to. We just have to keep looking.