Place squash, cut sides down, in a 13 x 9-inch baking dish coated with cooking spray.
Add water to depth of 1/2 inch.
Bake at 350 for 45 minutes or until tender when pierced with a fork; cool slightly. Using a fork, scrape spaghetti-like strands onto a platter; set aside, and keep warm.
Coat a saucepan with cooking spray; add oil.
Place over medium-high heat until hot.
Add leek; saut 3 minutes or until tender.
Add beans and tomatoes; cook over medium heat 5 minutes. Stir in olives and next 3 ingredients; cook until thoroughly heated. Spoon bean mixture over squash.