Heat a large nonstick skillet over medium-high heat. Coat pan with cooking spray. Add onion and pepper. Cover and cook 10 minutes or until onion is lightly browned, stirring occasionally. Uncover and cook 10 minutes or until golden brown, stirring frequently. While onion cooks, add 1 to 2 tablespoons water to prevent onion from sticking to pan. Remove from heat; set aside.
Preheat oven to 375°.
Unroll dough into a jelly-roll pan, and flatten slightly. Press handle of a wooden spoon into dough to make indentations at 1-inch intervals. Drizzle with oil; sprinkle with rosemary and salt. Bake at 375° for 15 minutes or until lightly browned; top with onion, and bake an additional 3 minutes or until golden. Cut bread into rectangles, and serve warm.