Place cut sides down in a 2 qt rectangular baking dish, add 1/4 c water, cover with ventilated plastic wrap and microwave on HIGH for 10-15 minutes or until squash separates when pierced with a fork. Rearrange once for even baking. DO NOT over cook squash or it will be mushy.
In a large skillet cook sausage, mushrooms, pepper, onion and garlic over med heat until sausage is no longer pink; drain fat.
Preheat oven to 350 degrees.
Scape pulp from squash (about 3 c) wipe out baking dish and coat with nonstick spray.
Spread half the squash in dish, add half the sausage mixture and half the olives.
Sprinkle with seasoning and 1/8 tsp pepper.
Top with half the sauce and half the cheese.
Top with remaining squash, sausage, olives and sauce.
Bake for 30 min, sprinkle with remaining cheese, bake for 5 more min or until cheese is melted.