Cook the squash: Use a sharp knife to cut squash in half lengthwise. Use a large table spoon to scrape out the seeds and string. Season with salt and pepper, place cut side up in a microwave safe dish and add about an inch of water to the bottom of the dish. Cover dish with cling wrap and microwave on high for 10-14 minutes. Allow to cool enough to handle before unwrapping. Use a table fork to scrape squash from top to bottom to separate flesh into strands of "spaghetti."
Prepare Meatball Marinara: Place meatballs in large skillet and cook according to package stove top directions. Once warmed through, add marinara sauce and cooked squash. Toss to cover and heat through; add Parmesan, salt and pepper, to taste. Serve right away.