1. Cut spaghetti squash in half (length wise). Scoop out seed from center. Put in baking pan cut side down. Pour in 2 cups water (enough to cover bottom of pan plus a little). Cover with foil. Bake 350 degrees for approximately one hour - depending on size. Test for doneness with a fork. Fork should pierce the squash easily. (if you like your squash less done then cook accordingly).
2. When done take fork/spoon and scrape out the fibers of the squash. Drain well to get rid of liquid.
WHILE SQUASH IS BAKING:
3. Brown up ground beef and Italian sausage. Drain. Set aside.
WHILE SQUASH IS BAKING ABOUT 1/2 WAY THROUGH (@30 MIN MARK):
4. Dice up onions and mushrooms.
5. Sautee onion in butter/oil. When onions start to brown add mushrooms. When done add in spaghetti sauce and/or fire roasted tomatoes. Heat til warm. Remove from heat.
6. Mix in baked squash, ground beef, sausage and parmesan cheese. Transfer to baking dish. Top with 1 cup. shredded cheese.
7. Bake 350 until cheese is melted and slightly browning. About 1/2 hour.
8. Remove from oven serve. Serve with spoonful of sour cream or plain greek yogurt.