1. Preheat oven to 350°F. In a roasting pan, toss squash, sugar, oregano, salt and 1 Tbsp. oil. Bake until tender, about 35 minutes.
2. In a skillet, cook onion and garlic in 1 Tbsp. oil until soft. Stir in vinegar, raisins and olives. Add to squash.
3. Increase oven to 500°F. Brush a large baking sheet with remaining oil. Form dough into 4 rounds on baking sheet. Top with squash mixture. Bake until golden, 12 to 15 minutes.