Acorn squash, halved and seeded • Plus 2 tbsp extra-virgin olive oil, divided • Salt • Freshly ground pepper • Chopped onion • Garlic, minced • Water • Tomato paste • Chopped chard leaves (about 1 large bunch) • 15 oz can white beans, rinsed • Chopped kalamata olives • Coarse dry breadcrumbs •