Halve the spaghetti squash lengthwise (remove seeds) and pre-cook in a shallow dish, cut side down, with about 3/4 inch of water.
Typically 30–40 minutes in a 350º oven will do the trick. After it has cooled, scoop the spaghetti-like strands of squash into a bowl and mix with garlic, olive oil, salt, pepper and parmesan cheese.
Return the mixture to the shell, add a little parmesan to the top and heat through. Set the oven on broil for the last few minutes to brown the parmesan sprinkled on top.