Heat oven to 400F. Lightly coat 13x9" baking pan with cooking spray. Cut squash in half lengthwise. Scoop out seeds. Place squash, cut sides down, in pan. Bake 40 minutes or until tender. Meanwhile, in large skillet over medium-high heat, saute SPAM 2-3 minutes or until lightly browned. Remove from skillet. Add bell pepper, jicama, onion, tomato, and pepper. Cook 5 minutes, stirring frequently. Add soy sauce. Bring to a boil. Return SPAM to skillet. Heat thoroughly. Fill each squash cavity with SPAM mixture. Sprinkle with green onion.